Well you need a compatible CPU because your motherboard was made prior to Ryzen 3000 CPUs. You try a local computer shop or contact AMD about a boot kit where they send you a cheap cpu to update the bios with and you ship it back. You could contact ASRock and send your board to them for them to do it. Or you could return your board for an X570 board that is compatible without a bios update.
If you still have your old CPU you can use it. You’ll find the latest bios on the support section of the ASRock website for your board. There is usually a utility that lets you do it in windows now that automatically downloads the latest one and installs it.