A2251 No power liquid damage - DFU

[tommy97]

Hi,

i'm having problem with A2251 Board after liquid damage was mainly next to CD3217 LEFT side & U9000, 3.3v, 1.5v, LDO's all on with correct measurements. Device cycling in between 0.10-0.20amp 20v, while battery connected goes to up to 2amps.

While trying to revive device, show error 4010 and then go to recovery instead of DFU, checked nand resistance no short, Ohm within the range.

[mon2]

Error 4010 is often related to network issues with the DFU tool in attempts to reach the Apple server.

What is the voltage to ground of PPBUS_G3H @ fuse F7000? Check both sides. If the voltage is not normal, flux and remove this fuse. Then meter in resistance mode, measure the resistance to ground on each side of this removed F7000 fuse using the PCB pads.

Post all measurements.

[tommy97]

While battery is disconnected it does show 12.60V, when connected it goes from 11.3v to 12.1v

[mon2]

12v6 means that the ISL9240 buck / boost regulator has been boosted to the correct value. When the battery is connected, it does not get boosted to the proper value. The SMBUS lines which are shared with the battery pack are used for this voltage shift.

Carefully measure the voltage to ground on the battery connector. Specifically interested in the SMBUS SCL and SDA measurements to ground when the battery is connected. This may mean that your BMS (battery management system) board on the battery pack is defective. Not 100% sure but Tim @ TCRS does chat in his videos about certain macbooks that require for a known good battery to be present in order to boot properly. This may be one of those models.