This PC has been working for almost 2 years, started after 4 months in storage ad everything was working fine. Update the BIOS through the setup utility, re booted without any issues. System ran fine. Added a Hitachi 3TB HDD, formated and accessable in Linux. Had piled paper on keyboard while tidying office and notice no video.

Swapped monitors with a known working monitor, no video
Removed MOBO from case, inspect, no visable issues.
MOBO placed on desk with 24 pin MOBO power and 4 pin CPU power connecters attached
Removed keyboard/mouse USB and memory sticks, powered up 2 beeps, 3beeps,3beeps,3beeps, no video
Reinstalled memory sticks and keyboard/mouse USB, no beeps, no video
Installed PCI Express 2 x 16 GeForce 620, no video
Clear CMOS, no video ether port

Are there any other tests to determine if the issue is the MOBO or CPU?

I don't have a spare AMD CPU