Random Crashes & bootloops

I've been facing this problem since buying the phone & it's been around 10 months. My phone is a K20pro Chinese variant, 6/128gb. From the very beginning, it was in Chinese rom v10.3.5.0 & I never could update it, whenever I tried to update after 1% the whole thing crashed & rebooted.

Then came the sudden crashes & reboots, my device auto crashed & reboots even without any load. I thought it was software issues so I used fastboot method to update to v10.3.8.0 but the issues still persist. So I unlocked bootloader & went to Xiaomi.eu & after a few stable days, it again started to crash & reboot. It's been like that for months, no matter what rom I go to the random reboots & crashes always follow & even now while I'm in Xiaomi.eu miui 11 beta it still crashes.

In fact sometimes it auto factory resets after crashing multiple times or boot loops by itself.

Now I think it's a hardware issue but I can’t quite pinpoint it, is it ram problem? Do I need to change the entire motherboard?