Dear reader

TL;DR: iPad not turning on, A10 and power IC become (very) warm when attempted to turn on but this power-on cycle has a 'cooldown' period wherein powering on doesn't work, does not take more than 0.5A charge.

I am working on an iPad 7th generation 2197 from >2019 with no / limited charging and no boot issues. It is a refurbished purchase made in 2021. It appears the 'refurbish' company has either done prior motherboard work (all protective component shield layers are gone) or is one of the many trash refurbish companies (little screen adhesive left, component shields removed, incorrect cable management/placement, loose and missing screws), of which I suspect the latter.

It has the following characteristics:

• No boot screen when turned on with power button
• Does not respond to multiple button-combo reset attemps
• Charges at 0.480A-ish for a bit, then goes to 0 with occasional 0.020A-ish spikes. I seem to remember someone on Youtube saying that he has made a connection between the 0.480A charging rate and a defective cap / passive component short
• With new battery the 0.480A-ish remains for longer, but still nothing on the screen when trying to power on
• Sometimes responds to power button, but not always. By responding I mean that the A10 chip and 343S00314-A0 power IC become very warm to the touch fairly immidiately, as well as some coils / bucks (?) such as L8113 near the power IC. This lasts for about 30-50 seconds, after which it won't respond to the power button input. It does not display anything on the screen during this

What I've done so far:

• Watched quite a few repair videos on this and similar ipad generation repairs with different faults
• Checked battery voltage, its at 3V
• Replaced battery (new one arrived with 4V state of charge)
• Resistance between battery ground pin and any non-component ground point on the PCB ground is 2 Ohms
• Tried to 'inject' operational voltage at battery connector with power supply (4.0V 0.5A), but it doesn't seen to respond to that. Perhaps because my power supply isn't very capable, as it does respond when the battery is used as a power source
• Applied IPA to detect hotspots
• Quick visual inspection of caps and other components
• Downloaded the schematics and components placement diagram

What I haven't done or can't do:

• Haven't changed screen
• Don't have tristar test tool
• Don't have thermal camera

I, as the repair person, have the following charateristics:

• No prior experience in Apple repairs, don't know what values are supposed to be or what common faults are
• Occasional basic schematics-based repair (audio, appliances), but the path line (VCC component path tracing and checking) diagnosis I haven't done yet
• Not a business, this is a 'I can take a look but no promises' handyman offer I made to the owner (whom I know personally)
• Hard to accept defeat in not finding the issue, but know my limitations
• Tools available: small but sufficient microscope, soldering iron, rosin flux, IPA, multimeter, USB power meter

Are there any suggestions where I can look and measure first, within the limitations I have (given my tools)? I'm not against asking or bringing it to a motherboard component repair shop, but there aren't many around in my region / country. Most 'repair' shops are replace-type shops, where they replace faulty components (camera, power button, etc.).

Thank you in advance.

Kind regards,

JB