Lenovo T14 Gen1 no power with a new battery after the original battery failed

[keepread]

Hi all,

Have a T14 gen1 20S1-S7A206 that threw up a battery error while being on a doc 100% of its lifetime. The user then googled the reset button trick and applied it about 5 times. That did not restore the operation. Instead, the laptop stopped powering on completely. I bought them a brand-new battery but still nothing at all: no indicator LED near the USBC socket, no LED on the power button, no start.
I can see that the laptop draws 0.4Wt power from either the portrable PSU or the docking station PSU. No lights on the docking station either.
Here's what I tried:
Disconnect PS, hold the power button for 1 minute.
Disconnect the battery and CMOS battery for 1 minute.
Hold the reset button for 20 sec.
All permutations of the above. Still no start, no light.
Any suggestions? Please help, the kid needs this laptop for school!

[Repdata]

Is the new battery an original product? Check the 19 V rail for short? The power supply goes into protection circuit

[keepread]

Check the 19 V rail for short?

How?

[mon2]

Believe there are multiple USB type C ports on this model? Test each USB Type C port with the power adapter.

Also attempt by flipping the same USB Type C port by 180 degrees to verify if the rotated side of the USB blade is working or not. That is, every USB type C port can be mated right side up; upside down - each has a different power path to the board. Test each permutation.

The power adapter is the original for this laptop? Would you have other USB C power adapters to testing?

What is the history of this unit? Just stopped working or was there a liquid spill? You have a multimeter to take additional measurements? Motherboard is visible?

[keepread]

The history is very simple: since new, it sat in its docking station, for about 2 years, was turned on in the morning and turned off in the afternoon, and had no spills or any other adverse treatment until one morning it was turned on and displayed the battery error. Then, like I had said: the kid reset it several times, every time getting the same battery error until it stopped turning on completely.

I have 2x original Lenovo PSUs: the portable 65Wt one and the docking station's 135Wt one. I was only able to test the latter and found 20V between its side prongs and its shield. Dunno about the portable PSU which I have never used until I received the replacement battery and tried this one first. I did try to flip the plug several times in the socket but only in the one marked as power (the top left corner). Now, I tried the only other USB-C port and got the same result.

I do not have other USB-C adapters

[keepread]

When I removed the old battery, I opened the film and measured the cells. The cell #3 was drained down to 2-3V, can't remember exactly (was 2 years ago), and ##1&2 were 3.9V. I charged all cells in the sequence 1-2-3, and ##1&2 took some 1000-1500 mAh, and #3 took some 6500 mAh if I remember correctly. Since then that old battery sat in my drawer because my charging the cells did not help. Its cells are still at 3.9V after all that time.

[mon2]

That was not what was asked. Charging at the cell is not condoned and is very dangerous and is a fire hazard.

Remove the battery from the logic board.

Attach only the USB Type C power adapter that was supplied with the laptop. Do you see any lights on the logic board turn on?

[keepread]

The laptop does not show any lights whatsoever nor does it start up, no matter what: with the old or new battery or without a battery.

[mon2]

What is the history of this unit? Just stopped working or was there a liquid spill? You have a multimeter to take additional measurements? Motherboard is visible?

[keepread]

What is the history of this unit? Just stopped working or was there a liquid spill? You have a multimeter to take additional measurements? Motherboard is visible?

I replied to your history question but it sits at #5 unapproved for some reason. I'll repeat, in the hope that this time the forum posts it Okay:

The history is very simple: since new, it sat in its docking station, for about 2 years, was turned on in the morning and turned off in the afternoon, and had no spills or any other adverse treatment until one morning it was turned on and displayed the battery error. Then, like I had said: the kid reset it several times, every time getting the same battery error until it stopped turning on completely.

I have 2x original Lenovo PSUs: the portable 65Wt one and the docking station's 135Wt one. I was only able to test the latter and found 20V between its side prongs and its shield. Dunno about the portable PSU which I have never used until I received the replacement battery and tried this one first. I did try to flip the plug several times in the socket but only in the one marked as power (the top left corner). Now, I tried the only other USB-C port and got the same result.

I do not have other USB-C adapters

I do have multimeters and o-scopes. The board is before me.

[keepread]

Another reply went into another unapproved post. Huh? I replied to your history question but it sits at #5 unapproved for some reason. I'll repeat, in the hope that this time the forum posts it Okay:

The history is very simple: since new, it sat in its docking station, for about 2 years, was turned on in the morning and turned off in the afternoon, and had no spills or any other adverse treatment until one morning it was turned on and displayed the battery error. Then, like I had said: the kid reset it several times, every time getting the same battery error until it stopped turning on completely.

I have 2x original Lenovo PSUs: the portable 65Wt one and the docking station's 135Wt one. I was only able to test the latter and found 20V between its side prongs and its shield. Dunno about the portable PSU which I have never used until I received the replacement battery and tried this one first. I did try to flip the plug several times in the socket but only in the one marked as power (the top left corner). Now, I tried the only other USB-C port and got the same result.

I do not have other USB-C adapters

I do have multimeters and o-scopes. The board is before me.

[keepread]

Everything I reply to you goes into unapproved posts. What's going on?

[mon2]

I can see your posts in this public forum ok. Perhaps because you have recently signed up for this website so may need additional permissions.

If you see 20v in the power path, this is a good start. This means the USB type C adapter is sending out the capabilities of the power delivery contracts (voltage & current paired combinations) that are supported -> the logic board is digesting this small database of values -> the logic board's power delivery (PD) controller (ThinkEngine on Lenovo models) is selecting the best PD contract to power the logic board (20V).

Locate the battery charger PU0201 (BQ25700ARSNR).

Nearby will be the dual mosfet PQ0201.

Measure the voltage to ground of pins 2-3-4 (any of them is ok). Red meter lead on one of these pins; black to ground (metal shield is ok). Meter in DC volts scale (30V or higher).

Do you see the 20V being supplied by the power adapter?

The other dual mosfet of interest is PQ0202. Measure the voltage to ground of pins 2-3-4-10 (any of the pins is ok). This is the main power rail (VSYS15) that powers the logic board.

The battery pack itself may be a factor causing this board to not boot so suggest disconnecting it for now.

[Document Archive]

Everything I reply to you goes into unapproved posts. What's going on?

Sorry about this. You put the word "spills" in your posts... we get a lot of spam mentioning pills so it's in the banned word list.

[keepread]

Sorry about this. You put the word "spills" in your posts... we get a lot of spam mentioning pills so it's in the banned word list.

LOL. I have a Jewish friend. His last name is Lipshits. It gets censored all over social media because many forum deployers don't know how to use regex

[keepread]

Nearby will be the dual mosfet PQ0201.

Measure the voltage to ground of pins 2-3-4 (any of them is ok). Red meter lead on one of these pins; black to ground (metal shield is ok). Meter in DC volts scale (30V or higher).

The other dual mosfet of interest is PQ0202. Measure the voltage to ground of pins 2-3-4-10 (any of the pins is ok).

Of all of them, I can only see short 2V spikes every 200ms on 2-3-4 of 0201. They appear as 14mv DC on my multimeter.
All other pins are 0V
I see a suspect capacitor now. Should I take it off?

.

[mon2]

Is it the cap with the off color? Sure, flux it and remove it. Then test the removed cap for its resistance. Test again without this cap.

[keepread]

The cap was short. Now, I have amber light from the power LED and white blinking light from the power button.
When I press the power button the blinking changes to solid lit white.
After a while, I get a few beeps, and the screen quickly shows a message about date not set and offers to ESC to continue or F1 to enter the BIOS.
I am in the BIOS now. Set date and time, F10, yes, boot into the OS.
Thanks a lot for holding my hand! I should have done away with the chipped cap but was too shy to deal with an unfamiliar device.



Do I have to solder the same cap back? What is its capacity/voltage?

[mon2]

Well done! All your work so far.

Check if your meter has a capacitance mode. If yes, remove all power and measure the capacitance across the other capacitor that is just south of the one you have removed. What is the value?

Openly, the removed capacitor will not be missed but of course continue to test and use it like normal to be sure. Based on the capacitance you measure, we can hunt down a replacement. Also interested in the voltage present here but likely will be the adapter voltage of 20v across the cap.

Would you have a micrometer? Measure the length & width of the cap that is still present on the board. Then we can nail down the SMD size of the removed part. It may be a 1206 or 0805 sized bulk capacitor. We usually order such parts from Digikey or you can consider to remove one off a donor board from similar power path circuits. That is, any other brand of a logic board will have also a power in of ~20v and caps on this main power rail could be used here.

[keepread]

They are 0805. Unfortunately no capacitance tester. Do schematics or boardview not show their values? A wild guess would be 2.2uF 25 or 50V but I go out on a limb.
The worst part I think is that the next cap parallel to the chipped/shorted one also shows some signs of chipping so might fail soon.