HP Laptop turning off frequently

Hello everyone.
My problem is that my laptop is constantly shutting down since January 19h or so. When I use the last command, I see that it says “crash.”
[username] tty1 :0 Thu Jan 21 14:47 - crash (02:12)
This happens even though the computer is not overheating, and even though I am not doing any intensive task.

Some backstory:
I have been living in a dilapidated, soviet town past 3 years. Since September 2019 I moved to an apartment, in a block with very bad infrastructure. Pretty much everything is explodin and getting overloaded all the time. Especially December festivities when everyone has extra flashing fairy lights turned on, even street lights go out. There’s a power outage almost every time it rains. My computer’s battery actually broke (won’t charge anymore) because of a power outage. Electricity is also not grounded here.

However, it is not a power problem this time. The computer doesn’t crash when I put it to sleep for 8+ hours before bed, only when I am using it actively. It is likely a hardware problem because it shuts off even when I boot Windows. I’m assuming that my computer got ruined by some power inconsistency this new year, although no outage has occurred this December or January.

I want to know what exactly could be wrong with it, in your expert opinion? Is there any way to tell why the computer crashes, such as whether it’s due to power loss, or thermal overload?
Journalctl does not give me useful information. I just want to know what I’m dealing with. Is death imminent and should I back up all information I have before it explodes completely?

Thank you.

Test the RAM with memtest86+ just to be sure.

I can’t use memtest86+ since I’m booting UEFI. Legacy mode is enabled in BIOS but there is no memtest option in grub anyway.
So I used the HP diagnostic tool, and it started doing a Memory Quick Test, passed in about 20 minutes. The disk check was right there too, so I also ran the fast version and it passed in one minute.

My last boot lasted a whopping 9 minutes before crashing. New low!