Big Sur upgrade and now Big issues

Hi Apple Community,

It's not my new thread on the issue but could not find my last post so decided to create a new one.

Like many of you I upgraded a few weeks back from Catalina to Big Sur confident that there would be no issue. but here we are 3-4 weeks down the line. I could no longer use Big Sur to the risk of overheating my MAC with potentially damaging it for good so decided to contact Mac Support to uninstall Big Sur and re-install Catalina which was working just fine. I followed up their step-by step guidance for macOS Recovery on Intel-based Mac computers. Something likely did not go well for no option was there for me to re-install Catalina but just Big Sur which I do no want any longer. This being said, next thing my MAC would no longer start and when trying to start up from macOS Recovery, my MAC would not display a message error -1008F.

Latest discussion with MAC support went like " we cannot help you downgrade MAC OS back to Catalina" but only re-install Big Sur (The culprit...). Kind of like running in circles here. So I will go get my MAC diagnosed asap now to see what's wrong. I must say I'm quite disappointed with MAC on this Big Sur upgradr. My Mac Book Pro dates from 2019 and Big Sur OS update just messed it all up for over 3-4 weeks now.