Question Laptop shuts down randomly ?

Feb 7, 2021
I am using Acer aspire5 a515-51g 8550u.

Few months after purchase it started turning off randomly when moved or lifted - it didn't follow normal shut down procedure. It was just like if you would suddenly pull the plug on a desktop pc. It wasn't because of overheating. Then one day it went completely dead. I tried replacing battery with a new one,but it didn't help a lot. Laptop would now turn on normally, but would still turn off randomly even when its not moved at all.

I tried disconnecting the battery and started running it on it's dc adapter only. This way it worked perfectly fine, until yesterday. Now, laptop enters BIOS mode automatically when powered on and doesn't boot windows 10. It stays in bios for a few seconds then powers off randomly. Before it turns off, I hear laptop fan's noise, as if it's running as fast as it can but there doesn't seem to be any sort of overheating.
Plz help.