Story time and a question:
Starting in late December, my S21 was randomly restarting about once a day. The issue progressed to the point where it restarted 5-6x in a row, a few times a day. The same time this started, I also faced issues with video playback not happening (or at 10x (ish) speed) and not being able to do anything with my Samsung account - I couldn't log in, couldn't backup data, couldn't run diagnostics.
I notice there's a software update and run this to see if it resolves the issues. On restart, I notice my SIM is not being registered and when I go into the SIM settings it is on constant loading (which is what happens when I try and do anything with the Samsung account so my assumption is it is related. Don't see how it could be a hardware issue if it started right after the update).
At this point, I want to run a diagnostic examination of the device so I can see what my support options are. Unfortunately, I can not run a diagnostic as it requires you to login to your Samsung account (seems rather backwards to me if your issue is you can't connect to your Samsung account).
The issues still prevail so I decide I need to try a factory reset. I start backing up my data on Google drive (as I cannot log in to Samsung to back it up their way) and midway through the restarts start happening. I should point out that the restarts happen regardless of whether the device is plugged in or not. 10 mins later when they stop, the screen is black. When I press the on button I see the time in the top left and occasionally holding down the power button brings up the power options - though none of them do anything.
I wait for the device to lose power and charge it up again to see if that fixes the black screen... It does. I finish my backup and I go to factory reset my phone... OH NO! I can't factory reset without confirming a log in with my Samsung account - something I can't do which is why I'm trying to factory reset in the first place!!
Anyway, I set my phone so it factory resets after 15 wrong login attempts and fail 15x. The device is factory reset yet the restarting issue still occurs and the no SIM and can't login issues still exist - HOWEVER they are now saying it's down to the device not having a IMEI. So same problem but given a different reason. Progress at least.
That is the current point I am at. The phone is 1.5 years old - what are my options for getting this issue repaired? It seems to be both software and hardware issues. I use the device as MFA so this is going to significantly hinder what work I can do next week.