Chosen Solution
I was just playing music on the phone while leaving it on the table, I wasn’t even touching it. But the music just stopped all of a sudden and there’s even a faint pop sound (seems to be from the speaker, not some component exploding) when it happened. Now the phone won’t respond in any way that I’ve tried including plugging it to a computer or pressing the power+home button for 20seconds. I am quite sure that the battery was over 80% when I started using the phone to play music. Is this phone still repairable or is it a complete brick now? Note: I have upgraded (just last week) to the latest iOS 12.1.2 hoping that it will fix the previous issue that I had with the touch screen not responding sometimes. Apparently it didn’t help at all, but I”m wondering if the update could have screwed the phone to the state it is in now?
Has this phone ever been repaired? If not, there are two highly likely solutions. Replace the battery. The iPhone 6 is about 4 to 5 years old. Even if the battery has been replaced before, its probably old enough to need replacing again.The charge chip (tristar I believe) needs to be replaced. This repair is not a DIY and requires micro soldering skills.
From the description you gave it sounds like something failed on the board and shorted. It could be a number of things on an iPhone 6 board that “spontaneously” fail and brick the phone. It could be Tristar itself of course, but in this case I lean towards a failed and shorted cap that “grounded” a major power rail. Think of it a bit like a main water supply pipe bursting and the water draining out instead of reaching the intended components.
I recommend that you have it taken (or mailed in) to be examined by a third party iPhone technician to determine the exact cause and possible solutions. For someone with enough experience, these are usually pretty straightforward and you should be able to regain both your iPhone fully functional as well as your data. There are cases where the storage chip (the NAND) that holds your data may have malfunctioned and died; in which case you can fix it but not recover your data. It is less common and I would bet on other things in your specific case.
