My PC won't boot or take input

Hi.

So recently, let's say during the past month, my PC sometimes would just go dead. I generally hibernate it bc I don't want to wait for it to startup and have to reopen all my apps. But sometimes when I press the power button, it's completely dead. So I tried switching power cables which worked for a while, but soon even that didn't work. I ended up doing a clean reset on one of the few miracle moments it did start (Win11 Pro). And for a couple weeks it worked perfectly, until it didn't. It either went dead or booted onto a blue screen that said diagnose device (paraphrasing here, you get it). Now, everytime I start it, it beeps once and opens onto a text screen saying 'date and time inaccurate'. There are options to boot or go to startup settings and what, but it's not accepting any input from my keyboard. Please help me someone.

Thank you in advance, and sorry for the essay but I felt I needed to be detailed.