Chosen Solution
Old iPhone I had laying around that I was going to give someone, but when I went to turn it on the battery was completely dead. I tried to charge it but it wouldn’t charge at all. No battery sign would show up. Just completely dead. Figured it was the battery, so I replaced it. Phone turned on, worked perfect. New battery charged just fine. Everything is working on it. Noticed the battery draining insanely fast (from 100% to 0% within 5 hours in standby mode) There didn’t seem to be a major difference in battery drain while I was using it vs just leaving it in standby mode. I noticed big drops when it came out of standby mode - like 68% showing first then instantly showing 56%. An official Apple charger will not charge it. A 3rd party charger charges it just fine. I’m thinking it’s the U2 chip, but just making sure.
If you have a computer running macOS available to you we can test the battery to make sure it’s working fine. Answering the charging question now, it’s worth a shot at changing the tristar IC (U2). Usually when a tristar IC is damaged an iPhone/iPad/iPod/etc. will not charge whatsoever, however in your case a 3rd party adapter will charge your phone but a genuine charger won’t. Still worth a shot though.
