Chosen Solution
My iPhone 6s Plus died. I was using it and power just cut out and now will not power on. I tried the iPhone reset, different power adapters, as well as connected it to computer to make sure it was not powered on but no screen. All to no avail! I read in a few places to try the battery and the lightening connector. So I tried both from iFixit and neither resolved the issue. Some replies here have stated the charging circuit but if it was that then the new battery from iFixit would have worked for awhile at least as it comes with a charge. Any other thoughts on what I can replace?
You are mostly correct in your assumption that if the damage was limited to the charging circuit, then the phone would have worked at least while the battery holds a charge. It all depends on how much damage and where exactly it occurs in the charging circuit. It also depends on what caused the issue in the first place. Was it spontaneous component failure or something like exposure to water, drops (multiple small ones or one big one), prior repair attempts… If you have already replaced the battery and charge port with iFixit parts, then it is pointing more and more towards the logic board. The problem with buying one-off parts is that you never really know if they are fully functional or not. A quick trip to a local repair shop may put that issue to bed. The iPhone 6S also has a recall in place for unexpected shutdown issues, you could always try your luck with Apple if your phone is eligible. Otherwise, if you isolate it down to a logic board issue, then look for a reputable micro-soldering repair shop.
