iPhone 6 suddenly not charging, not receiving current
I have received an iPhone 6 just shy of two years ago as a gift. I assume it was a refurbished unit since Apple stopped selling this model in 2016. A few days ago, I unplugged it from its charger, used it to the point it needed charging again, plugged it back, then nothing. It wasn’t charging. I did swap chargers/cables, third party, other brands, and of course original Apple, to no avail. Doesn’t even turn on when plugged in.
Had a Genius Bar appointment, had it checked, apparently their special tool could read the serial number and some other things I didn’t understand, but wasn’t pulling any current. Since it’s out of warranty (What a shame to provide 1-year warranty on such expensive devices!), the Genius mentioned a full replacement would be the same price as a brand new one, but advised against it since that would make for a pretty expensive iPhone 6 (about $400 before taxes).
The only issue I had with this unit so far was its enourmous power drain: 5 hours of moderate usage would run the battery dry. Battery Health 3 on the Mac reported 85% health, and of course, an unusually high number of cycles. Never took any water, no strong shock (I have a decent bumper).
From a quick search on the Internet, either the Lightning port is to blame, or the U1401 charging chip. How do I know what is the faulty part?
On the downside, I don’t have any microsoldering tools (I could never justify buying hundred $ of equipment “just in case”), nor skills for that matter. I saw some repairmen (and probably women too"!) advertising their services on eBay (All based in the US, so I’d have to add larger shipping fees as well as customs if I’m unlucky), but nothing local. Worse, iFixit doesn’t sell unlocked iPhone 6 boards. A few ones come up on eBay, though not exactly cheap at $120+.
What would be the best course of action?