Macbook Pro 2015 13" power problem

[andy2000]

I'm working on a Macbook Pro 13" early 2015 A1502 model with a weird set of symptoms.  I have already found the schematic and board view files, but before I spend hours on it, I'd like to hear any tips, or known faults.

It was described as dead, no power, but that wasn't exactly true.  With a charged battery, it will power on and work perfectly.  I've had it running all day with no issues.  It sleeps, and restarts fine.  It passes all the diagnostics.  It charges the battery, it runs from the battery or AC (a working battery seems to be required for this model, as it won't work at all with no battery connected). 

The problem is that if you turn it off, it goes almost completely dead.  It won't power on, or charge the battery.  The only sign of life is that the orange/green LED in the power connector does correctly indicate whether or not the battery is fully charged even though it won't charge the battery.  Also, the SMC reset key combination results in the indicator LED briefly turning off.  There is still a voltage across the power button, and I have confirmed that the keyboard power button works.  I have tried clearing the PRAM with the key combination, but it didn't help.

At this point, the only thing that will make it work again is to disconnect the battery and AC power for somewhere between 30 minuets and a few hours (I'm not sure what the exact threshold is).  After I reconnect the battery, it will turn on as soon as I either hit the power button, or connect the power adapter.  It then works again until it's shut down.  Note that this model has no CMOS battery, so disconnecting the main battery is equivalent to removing the coin cell from a PC. 

The laptop is in immaculate condition with no signs of liquid damage, and no sign of prior repair attempts.  I'm going to start by connecting the battery and checking all of the power supply rails before it has been turned on, then I'll turn it on and shut it down and recheck the power supplies.  If that reveals nothing, I plan to start poking around the SMC chip.  Does anyone have any other ideas?

[CMIzapper]

That model will work without a battery. Except that it runs at about 1/3 of the speed without the battery.

[BradC]

The problem is that if you turn it off, it goes almost completely dead.  It won't power on, or charge the battery.  The only sign of life is that the orange/green LED in the power connector does correctly indicate whether or not the battery is fully charged even though it won't charge the battery.  Also, the SMC reset key combination results in the indicator LED briefly turning off.  There is still a voltage across the power button, and I have confirmed that the keyboard power button works.  I have tried clearing the PRAM with the key combination, but it didn't help.

This won't help, but I encountered exactly the same symptoms on a friends Macbook Air earlier this year. It was under extended Applecare so they had Apple replace the mainboard.

On the other side of the coin I love my A1502s.