I have no clue how-to : TV auto-starts with Android no buttons and LED fast flicker

[Ancient1]

CROWN Smart TV, 50", Single board design

1. TV starts with Wall power..
2. The front LED is blinking very fast that it looks like a red&green LED
3. The Android Menu in the photo appears
4. Buttons are not responsive

I tried few pre_Power Button Combos, and with Power, but none worked

I'm scratching my head how to start diagnosing.. ??

[dskall]

Re: I have no clue how-to : TV auto-starts with Android no buttons and LED fast flick

Looks like maybe firmware problem. You've taken remote batteries out and unplugged your buttons on tv?

[Ancient1]

Re: I have no clue how-to : TV auto-starts with Android no buttons and LED fast flick

Hi . Thanks for the feedback

I don't have the remote. Tried my Univesal Remote codes for the Brand, but IR doesn't look like its about to respond..
Can it be Stuck in flickering ( thus unable to respond to buttons/remote ) because of some electronic component like a Cap ...

The LED blinks Red/Blue few times than start to flicker very fast.
I did unplug the IR board , than the cable for button and IR & LED : Cable to Wall :
* TV comes up with same Android Recovery screen
* Reconnected the cable ( TV is ON ) resulted in SAME flicker and stuck buttons.

I have searched for Firmware for the Board : HK.T.RT2851P838 , but can't find ANY mention online , though I see few versions : some with 2871 , and others with 939.

I did not find ANY mention of such a wierd situation. I mean, usually the TV would show the Logo , right ?
I shorted the 2 plug pins , and leave it for the night. Hardware looks good.

[Diah]

Re: I have no clue how-to : TV auto-starts with Android no buttons and LED fast flick

how will you gain control on the set with out RC !!! ?
plug USB mouse and in recovery do delete cache then factory rest to see if it help

[Davi.p]

Re: I have no clue how-to : TV auto-starts with Android no buttons and LED fast flick

Hi, probably on the main board in the path of the keyboard line there's a protection cap or diode that is shorted to gnd..

[lotas]

Re: I have no clue how-to : TV auto-starts with Android no buttons and LED fast flick

Hi, probably on the main board in the path of the keyboard line there's a protection cap or diode that is shorted to gnd..

No, the problem is in the firmware.

[Davi.p]

Re: I have no clue how-to : TV auto-starts with Android no buttons and LED fast flick

R U sure 100%? If not an uart connection to log can reveal the misfact.

[Ancient1]

Re: I have no clue how-to : TV auto-starts with Android no buttons and LED fast flick

Hi.
I woke up at 02:45, as I was waking I was dreaming about me proudly presenting a repaired TV , and I continued thinking :

The TV fools us with the Android Recovery being the issue, requiring a Factory Reset of new Firmware.

* There is a Buttons Board , IR and LED Board, both end up on same CON - see Photo
* I disconnected the relevant cables but the TV acts the same.
* I tried connecting USB KBD and Mouse : as I suspected : no reaction.
* I tried Universal Remote with "Crown" codes : no success.

What happens when I plug the TV to the wall :

• 2sec Red LED
• 4sec Red/Blue flashing
• Fast Flicker , and the Android recovery is coming up

I did try of course Button/Key Combos :

Sources & Vol (-) , than with ON key
Sources & Vol (+) , than with ON key
No change in TV behaviour.

What I realised at night is that the Android Recovery screen isn't the problem , but the locked/frozen Buttons.
Doing Factory Reset isn't the issue, but ACTUALLY doing the Factory Reset

• TV starting with wall plugging isn't normal i.e PS_ON is Stuck : AFAIK, it is the CPU job to direct V_STB to PS_ON/BL_ON lines (its a single board here )
• 2 seconds Red light is normal and than the TV signals an issue for 4 seconds of Red-Blue normal flashing.
• CPU detects the problem signaled in 4sec Red/Blue and sees it as Android issue ? Would failure to Load the OS cause the LED to signal error ? Perhaps its EEPROM V issue
• Than we get the Fault State : Android and V.Fast flickering - the LEDiode is switching as fast as it can. And, the Buttons and IR seem to be in Arrhythmia, needing a Defibrillator.

I think that asking why the TV autostarts ( and signals an isue) might lead to the cause better than the approach from the end result of the proccess.
Davi.P suggested "on the main board in the path of the keyboard line there's a protection cap or diode that is shorted to gnd" - he "entered"through the Buttons, but this must be connected with the Autostart.

* I am inquiring about the possibility of a spike through the HDMI : No, they use only the router.
* I'm going to take Main out ( SINGLE board design - see earlier photo).

[Davi.p]

Re: I have no clue how-to : TV auto-starts with Android no buttons and LED fast flick

Ah, one moment, i forgot to read all the screen message, in fact it is saying that there is a problem with the firmware, probably the userdata partition, the fact that tv autostarts it's normal, every tv has an autostart flag, when tv is not turned off by buttons but by unplugging, the flag "running" is set and next plugging the tv autostarts, this let me thinking what i always thought that is, when tv is unplugged or tension fall occurs and smart tv functions are writing data on to user partition, an error occurs in file system and prevents next normal boot, now the mistery is why buttons no more works, i mean those of local keyboard, the rc in recovery doesn't work... you should check the keyboard with tester because you can have 2 problems.. or maybe the error in user partition and its mounting stops the os loading and it hangs up with standby sw no more running keyboard driving. To escape this situation 4 are the ways, one changing the board, two reprogramming directly the chip, 3 reprogramming by usb key in a certain way, 4 accessing the os via pc+uart and making one of two: forcing usb key upgrade, or going in to shell and repair userdata partition (very difficult) , i add a third option, entering the shell, finding a command that shuts off the tv then with local keys accessing recovery mode and perform a recovery.

[Ancient1]

Re: I have no clue how-to : TV auto-starts with Android no buttons and LED fast flick

Davi.p

I measured the Buttons Con. :
5V Pin = 5.15V stable.
Power Button = 3.3V , goes to 1.0V on press
All buttons have 3.3V , but on press go down to different V , I assume that is how they are recognized/identified.

"4 are the ways, one changing the board : just one offer on Aliexp for $83, two reprogramming directly the chip, 3 reprogramming by usb key in a certain way, IF I can find the Dump ! I tried.
4 accessing the os via pc+uart and making one of two: forcing usb key upgrade No Dump, or going in to shell and repair userdata partition (very difficult) , i add a third option, entering the shell, finding a command that shuts off the tv then with local keys accessing recovery mode and perform a recovery. If this 3rd option will enable the keys than the issue is solved

So to sum up : The issue is to release the buttons in order to perform Factory Reset which seems to be proper functioning of the system.

So how to pc+UART ? how is the procedure called , so I can Google

* Added Service Manual for the board

[Davi.p]

Re: I have no clue how-to : TV auto-starts with Android no buttons and LED fast flick

keyboard is working , when i say the word upgrade it means with official file from manufacturer's site, when i say directly programming the memory i mean with dump. Sorry sometimes i am too long in my posts, i have named uart way but i'm unable to guide you through this path 'cause every tv chassis is different and requires long deeping / diving and sometimes fails due to protections, let me take some time to reflect..

[lotas]

Re: I have no clue how-to : TV auto-starts with Android no buttons and LED fast flick

Uart - pin.

[Ancient1]

Re: I have no clue how-to : TV auto-starts with Android no buttons and LED fast flick

Davi.p
I asked for a name for the process so I can Google.

lotas : !! and good eyes too


Uploaded Board close up, and 2 captures from the Service Manual ( Iranian Manufacturer ) : It speaks of Factory Menu and entering a pass.. but how if IR isn't working

[Ancient1]

Re: I have no clue how-to : TV auto-starts with Android no buttons and LED fast flick

Access using UART
watching some videos to get an idea

[Davi.p]

Re: I have no clue how-to : TV auto-starts with Android no buttons and LED fast flick

Watch YTube video especially those of iFix

[Ancient1]

Re: I have no clue how-to : TV auto-starts with Android no buttons and LED fast flick

iFixit ? or ? give me an example ?
and regarding what ? UART ?

[Davi.p]

Re: I have no clue how-to : TV auto-starts with Android no buttons and LED fast flick

ifix ifix channel, related to pc-tv interfacing , uart log, etc..

[lotas]

Re: I have no clue how-to : TV auto-starts with Android no buttons and LED fast flick

https://www.youtube.com/watch?v=uSuFVntxRg0

[Ancient1]

Re: I have no clue how-to : TV auto-starts with Android no buttons and LED fast flick

lotas : already watched this

So what I understand is that its quite simple - once you pair TX & RX to their counter pins, you install the drivers for the UART, PuTTY on windows , find the BAUD and start talking to the device
I built once the cable and used SPIPGM.EXE to flash BIOS to unpowred motherboard. This seems similar, perhaps easier, since the UART is powered by the USB, and in my case, RX / TX are plainly marked on the board.

I'm seeing quite a few options for such USB-UART devices in Aliexp. confusing

[Davi.p]

Re: I have no clue how-to : TV auto-starts with Android no buttons and LED fast flick

Wait... useful uart is not that one inside a desktop PC, it is a 3v uart like in many Programmers, CH341A the most cheap..