I don't know if they're still doing this (I assume so), but AMD has a "Short Term Processor Loan Boot Kit" where you can get a loaner CPU to update your BIOS:
https://www.amd.com/en/support/kb/faq/pa-100But, with my experience with Asus' X570-I Gaming, I'd just return it and replace it with their B550-I Gaming. That board has BIOS Flashback, a front-panel USB-C connector and, most importantly, a chipset fan that won't drive you crazy (of course that could be simply a bad board in my case):
https://rog.asus.com/forum/showthread.php?128486-How-Loud-is-the-Chipset-Fan-on-the-ROG-Strix-B550-I... I returned my X570 to Amazon without problem, got a store credit (I wasn't sure if I wanted to go the B550 route at the time), and then got the Asus B550-I Gaming later. No problems with it except it has one fewer USB connector on the back than the X570-I does (and I need that extra connector).