Dead no power, 0.25A when press power button

I have an iPhone 6 here from a customer, no water damage etc, but completely dead.

I’ve tried standard stuff like battery etc, and when connected to DC power supply it will be on 0 until I press the power button, then it will sit steady on 0.25A and get slightly warm near the CPU area, can’t find any shorts etc so a bit lost on this one, is this a CPU or PMIC issue?

Many thanks!

Harry

Update to this, When power is connected there's a short on VCC Main, when power isn't connected there's no short.