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Right to Repair


Released September 25, 2015. Model A1687/A1634. Repair of this device is similar to previous generations, requiring screwdrivers and prying tools. Available as GSM or CDMA / 16, 64, or 128 GB / Silver, Gold, Space Gray, or Rose Gold options.

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replaced battery, no longer reporting state of charge correctly

I replaced the battery and Taptic Engine yesterday. I drained the phone till it powered itself off. Then I charged it overnight to 100%. Today it never dropped below 99%. Finally I decided something was wrong so I rebooted. Then it said it was at 55%. Shortly after that it rebooted and it continues to reboot. I pulled the phone apart again and inspected both connectors under a microscope but I don't see any damage or indication they were improperly mated. There are no exposed components near the connector I could have damaged.

Worst part is there wasn't anything wrong with the battery. I needed a new Taptic Engine but I decided if I'm already going through the trouble of opening the phone up I might as well replace the battery too.

Only thing I can think of is a defective battery or I broke something with all the gentle prying required to get the thing open.

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2 Answers

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Stop, rewind. iPhone 6+ series (6+ and 6S+) have such huge batteries that it's almost never the original battery that's failing unless you damage it say by prying at it, or from liquid ingress. I have yet to see a bad 6+ battery that just dies on its own, and 6S+ are more recent.

On the other hand, bad replacement batteries are THE RULE, not the exception. In addition, the symptoms you are experiencing are exactly those of a bad battery: reporting wrong percentage, and boot-looping (restarting).

So I hope you did not damage or throw away the old battery and I would definitely put it back if I were you, or get a replacement one from (they are my go-to supplier for good quality batteries and if a bad one slips through their QC, you're covered by their warranty. IMO it is way cheaper to pay a bit more, install once, than ruin the phone and repeat the job a few times.

Second, Tristar symptoms, among others, are: no or spotty connection between computer and iPhone; slow charging + fast depleting; no charging or saying it is charging but no increase in battery %, and sometimes decrease in %; phone works, charges if battery is partially charged, but unable to charge a battery from 0% and restart the phone.

And finally two words of advice, from someone who's been into iPhone board repair for a couple of years:

- Never ever replace anything in a phone that's not proven bad, you may get yourself in trouble just like now.

- If you're intend on trying micro-soldering and micro-BGA rework, train on scrap boards of the same configuration and the same thermal mass as the device you want to fix because you're otherwise likely to shift components, tear pads, and in general render your device useless. I've seen horror stories from so-called trained technicians. I dare not imagine what an enthusiastic amateur will do on his first ever trial.

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I would try doing a couple soft resets (Hold power and home button), and if that doesn't work, try putting the original battery back into the phone and then soft resetting. It could just be a bad new battery, but worst case it could be the tristar chip on the logic board.

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After reading the symptoms of a failed Tristar, I'm going to guess that's it. My phone does all those things. I can't think of how I damaged it other than ESD. Can I purchase this chip? I'm actually an electrical engineer and have all the PCB rework equipment necessary to change the chip. Probably not the ambition though...


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