Doesn't that motherboard have dual bios? Use the Bios_SW1 switch to boot the 2nd bios. Go into m-flash, switch back to the corrupt bios & flash MSI original. I think all the new MSI motherboards also have a usb bios recovery. Did you read your manual??
"BIOS_SW1" is the multi-BIOS switch which got two built in BIOS "BIOS-A" and "BIOS-B". When BIOS-A failed to boot up, you can switch to BIOS-B and boot up your system. Applicable Models: X299-GAMING-M7-ACK X299-GAMING-PRO-CARBON X299-GAMING-PRO-CARBON-AC X299-RAIDER X299-SLI-PLUS X299-TOMAHAWK X299-TOMAHAWK-AC X299-TOMAHAWK-ARCTIC X299-XPOWER-GAMING-AC X370-XPOWER-GAMING-TITANIUM Z170A-XPOWER-GAMING-TITANIUM-EDITION Z270-XPOWER-GAMING-TITANIUM MEG-Z390-GODLIKE Z370-GODLIKE-GAMING The MPG Z390 GAMING PRO CARBON AC has only a JBAT1: Clear CMOS (Reset BIOS) Jumper