Origineel bericht door: Minho ,
Tristar (U2) doesn't really communicate at all with the battery so that's not likely to be the source of your problem. You say the phone worked while plugged in but if you left it unplugged, the battery dies within a few days; is that correct? The problem is likely in the charging circuit, in this case the PMIC, MOSFET, and associated passives. Ideally, this will need to be looked at by a micro-solderer as it requires board-level diagnostic.