A1989 820-00850 does not boot when battery is connected

[donnos]

Hi All,

have this macbook came in issues not able to turn on, found out the battery is blown(literally having holes in it). tried to do a battery swap and its still not booting up. However without battery connected, macbook boots up fine.
Tried battery from another vendor, macbook boots but does not charge, system reports detects battery data and shows battery "service recommended". this at least tells me that the SMC/T2 is working.

Tried changing ISL6240 chip and still the same. all 4 ports working fine,
Checked current sensing resistors all good, and no visible water damage anywhere on the board.
when battery connected macbook is stuck at 20V 0A, ppbus is low 4v< (normal at 12.6v when no battery connected). any hints for me to continue troubleshooting this?

[mon2]

Measure the voltage to ground of the SMBUS (SCL & SDA) lines of the battery connector.

Post the readings.

Update:

After the above, check the operation of the BATTERY MOSFET @ Q7065. Measure the voltage to ground of each mosfet pin cluster:

source (1-2-3)
gate (4)
drain (5-6-7-8)

Post the readings.

[donnos]

This is resolved. SYS_DETECT_L is internally broken at the battery data cable.