[Galaxy A3, A5, A7, A8, A9 Q&A, Help & Troubleshoot] Bryan48765:
Maybe I did something different, such as pressing volume up, or holding both volume down and power. Or volume, power, and home. It's the last thing I remember doing before seeing it fast charge again. Odin and fast charging simply didn't, within at least a year of trying different cables, and chargers offered by others. The shop I bought it from cleaned the USB port but it didn't work. The fast charging works today, and the Odin flash worked.

The context was that I have replaced that phone, so I tested a few things on the old one that could brick it or damage the EFS. If it happens, I could load the backup on TWRP. If TWRP becomes unavailable, that's unfortunate. The phone didn't have much value anyway because the USB functionality, power, volume down, microphone, speaker, battery, etc were defective, many cosmetic defects, and the phone was permanently rooted. The SIM 2 tray's front broke off, the SIM became inaccessible (I have deactivated that SIM). Wiped the cache,data,internal storage on TWRP, before testing. I left the phone on. Battery went to 0%.

These are what I remember doing(might have done), most of these could, of course, brick the device, damage the efs, or permanently damage the hardware. Not in any order. I don't recommend anything below unless you have replaced your device, try different button combos, like the ones above.

Left the device on for ? days. It did not pass the new year.

Soundalive, Adapt, SecurityLogAgent were debloated.

*#9900# > SilentLog > whatever is on the screen. (Not 9090, the RAMDUMP (ON) could resize and damage the EFS partition!!!)

*#9900# > CP based log.

*#2683662# > DSP Log on, RmPC log on, RF log on (3).

*#9900# > Debug Level > high. Device rebooted itself.

Took a look at the logcat -b radio, it got more verbose. Cellular related, and there's hexadecimal that I was too lazy to decode.

build.prop dev.silentlog.on It set the option on, but with no effect? I don't remember if I had checked /data/log.

efs > factorymode > on, maybe? It didn't change anything, probably did not do this.

build.prop ril.OTPAuth=true

build.prop ro.build.type=eng It didn't work. Setprop... it didn't work. Reverts back to user.

The power and volume down... against the rounded edge of a table. Did not use force, it got those buttons unstuck(power permanently on, volume permanently off). Power button sometimes presses itself, but at least it isn't (almost completely) permanently like the way it was. Of course it could get rust all over the other components, get the accelerometer stuck, get those buttons permanently embedded, etc.

Turning both microphones towards the earth's gravity, inserting the SIM pin, then spinning it got the microphone working again. I don't recommend this. "OK, now only the USB problem is significant".

Set *#2683662# logs to the defaults (all off except RmPC), *#9900# debug level low, load backup in TWRP (data,system at least). And then the phone was left on at the lock screen.

Found it with a dead battery. Fast charge worked again.

I then flashed stock Nougat on it, then it got rooted. Gave it since it's no longer my main device. The recipient is afraid of it for some reason. Offered an underclock because the device gets hot while under load... nope. Guess it's the power button being odd sometimes. The speaker remains muffled & the sim 2 tray is stuck. But for now, I still have access to it after asking for permission, to copy & look at system files.

The battery is old and shuts off quickly below 15%.