Chosen Solution
I replaced the rear housing of the phone and it’s now getting really hot when I turn it on. The voltmeter keeps changing when I’m measuring the poles where the battery goes in from 4V to 0.4V. I’ve also replaced the power button but unplugged that and got the same result. The phone turns on after taking ages to charge but shows the home screen while the CPU gets really hot. I’m now wondering if it’s the IC issue but I don’t know how to check it.
You may be able to find your answer here How to I test the Tristar? Good luck
The breakout board style tristar testers are total garbage–they have too much noise and the problem of integral damage to fine traces within a chip does not produce a diode mode detectable change in resistance at the scale we can detect signal to noise. However, a German guy developed a digital tristar tester that uses a functional test of the tristar lines and that has proven to be an indispensable tool, at least in our shop. It is too expensive to make sense for DIY, but most independent repair shops will have one these days and it doesn’t hurt to ask to borrow it for a minute. This is the “good” tristar tester. https://ipadrehab.ecwid.com/#!/Digital-T…
I would give this a try : https://www.ebay.com/itm/Professional-Ch…
