A few Gen 3 iPads with differing charging issues (A1403, A1430, A1416) & iPad Air 2 (A1566)

[Aimbit]

I purchased some broken iPads (non-charging), trying to repair something a little trickier than retro consoles... I have all the necessary tools.

A1430 - Draws 930mA consistent, screen is black with red/empty battery icon, no charging symbol.
A1403 and A1416 - Draw 930mA, wait 3 seconds, dip to 0, repeat.
A1566 - Similar to the previous issue, it draws some power for a few seconds, then resets my ammeter, and repeats. Waiting for my lightning port tester to come to check the tristar.

Seeing as these are old, and likely have been dead for ages, is a battery replacement more reasonable than jumping right to the charging IC's on the Gen 3, and the Tristar on the iPad Air?

I'd appreciate any advice!!

Thanks

[Aimbit]

So… I hate that this worked, but on the A1430 iPad I tried this “trick” of basically running a hairdryer on the back of the iPad to heat it up and then it magically will charge…

It seems to have worked as it has now booted and has 23% battery. Going to let it go overnight and see where we land with that.

The theory, and this may be 100% made up is something about a sensor in the battery, and when heat is applied to it it allows a charge to start. No idea if that holds any water.