I recently bought a Ryzen 5500 and an MSI A-520M-A Pro motherboard, but my Ryzen 5500 won't boot on this motherboard. Unfortunately, I don't have the budget for a different CPU, and the motherboard doesn't support BIOS flashback. Does anyone know how to update the BIOS without a CPU?
2 Answers
If your motherboard doesn’t support USB BIOS updates, one workaround is to buy an older compatible CPU, update the BIOS, and then return the CPU if the store has a good return policy. Just make sure you check if they accept returns.
Unfortunately, it looks like you really can't update the BIOS without having a compatible CPU in place. The motherboard needs to be able to post in order to perform any BIOS updates.

I've heard that some shops could do the BIOS update for you, maybe for a small fee. It might be worth asking around at local computer repair shops.