Now the new problem, I'm unable to get display after powering on pc. (Continuous long beep is still there, I disabled those warnings for CPU fan and system 1 fan)You mean time/date resetting back to some fixed year in past or settings reverting to default settings? If yes then try changing cmos battery/button cell.
I tried every method. But I get display only after removing and reinserting CMOS battery, and bios gets reset.
Can I revert back to previous BIOS version?