Report your pc model would be helpful.

Dell Optiplex 7050 SFF Desktop PC Intel i7-7700 4-Cores 3.60GHz 32GB DDR4 1TB SSD

Try replacing CMOs battery W a new battery 

Sorry it is a 7010, not a 7050

more reason to replace battery if it is legacy 7010. where did you get the i7-7700 info if it was a typo in 7050?

The "Previous thermal failure" message doesn't always mean the CPU actually overheated. It can also be triggered by a failing temperature sensor, a CPU fan that's not reporting the correct RPM, dried thermal paste, or a heatsink that isn't making good contact. I'd check the CPU temperatures with a tool such as HWiNFO or HWMonitor, confirm the CPU fan speed is being detected correctly in the BIOS, and inspect the heatsink mounting and thermal paste. If temperatures are normal but the warning keeps appearing, the issue may be with the fan or motherboard sensor rather than actual overheating.

What is a suggested quality battery replacement?

I buy Toshiba cr2032 pack of 5 on eBay. It often comes handy to maintain old legacy pc.

If red uses Toshiba, then it's a good battery.

I stick to Energizer.  I get a good 5 years or more out of them things.  I never had an Energizer leak.