Was the mainboard working correctly with some earlier model of Rytzen CPU prior to the installation of the 5700G?
(If so, was the BIOS updated to one allegedly supporting that CPU beforehand? No certainty that out-of-the-box BIOS will support the 5700G, or any 5000-series Ryzen prior to a BIOS update)
If the proper BIOS was done, I'd remove power from the PSU, remove BIOS battery, hold down Power switch for 10-20 seconds, reinstall battery, reapply power, and wait a full 2-3 minutes, perhaps a few resets, as BIOS reprobes new hardware...