Ask HN: My Samsung phone suddenly stopped accepting my password, any ideas why?

I noticed my phone was heating up unnaturally so I restarted it. After the restart, it won't accept my password anymore.

When I input my password and press done it will just ignore it and turn off the phone due to 5 seconds of inactivity meaning it won't register my password. If I press around to prevent inactivity, it'll tell me my password is incorrect after 6 seconds.

Notes:

- I have never changed my password and have no evidence of being hacked on my google account

- It validates any password <4 characters immediately with incorrect but anything above that will "hang"

- I was told to put it into safe mode by support which locked my phone into airplane mode

- Hard reset doesn't do anything

- Wiped the cache partition in recovery mode doesn't work

I've left it with Samsung technicians to see what they can find out and an explicit note not to factory reset it. That is an absolute last resort. The only bad symptom I can think of is that my phone space was running really low.

I got complacent and did not back up regularly like I should and this seemingly random event caught me by surprise. Has this ever happened to anyone else?