Start up error

[Brampton70]

Since installing a Windows 11 upgrade the deaktop computer will not boot up correctly. when power is switched on it starts without pressing the on switch, then shuts down, starts again and shows an error CMOS Reset (502). It eventually continues to load and works correctly, except that the time, date and screensaver are not loaded, although this also eventually corrects itself. 

Any suggestions please

Thanks

[Williamjoe]

Start the system to the installation media for the installed version of Windows. 
On the Install Windows screen, select Next > Repair your computer.
On the Choose an option screen, select Troubleshoot.
On the Advanced options screen, select Startup Repair.

Regards,

Will