I have been repairing a water-damaged MacBook Air 2015. Initially the machine would only boot with the battery disconnected and power connected, but then die after around 20 minutes. The MagSafe light did not light up at all but still provided power to the computer.
I replaced the battery, which made no difference. I replaced the logic board which then allowed me to boot with the battery & power connected. The MagSafe still did not light up and the the computer would die after around 20 minutes.
I have just now replaced the I/O board. The MagSafe still does not light up and the battery does not charge, but the computer runs as normal with all apps open and full backlight etc.
I have reset the SMC and PRAM to no effect but I can't think what I could possibly replace at this point. The only remaining original part is the ribbon connector that links the I/O and Logic board but that looks in good condition. Does anyone have any suggestions at this point?
System report says that there is 0 mAh charge remaining in the battery
It also says that cycle count is 729 which it definitely isn't as it's a new battery.
Any help appreciated.