It should work with only CPU_PWR1 (8-pin) connected..CPU_PWR2 (4-pin) is power for increased overclocking potential.
BIOS version 7B79v1A
adds support for Ryzen 3000 series CPUs..You need that one or newer and almost certainly guaranteed that's what the problem is..There have been 8 other BIOS updates, not counting the original, prior to that one..I'm pretty sure your board just has one of the older BIOS versions.
See: How to flash the BIOS
Either flashing from USB in DOS might work, or using M-FLASH, I can't say for sure..If not, take it to a PC repair shop or install another/compatibile CPU to flash it up to the latest BIOS..Then you will most likely find joy.