I've done this in the past and it works for me, not sure it will work for you but there is hope in trying, I bought some rx580s from aliexpress years ago and two of the rx580 came with an issue similar with yours, I don't have the BIOS backup, I find them online using google and flash the BIOS using HiveOS..

The best BIOS flasher is HiveOS, it always go smoothly, not familiar with HiveOS? You need to watch some videos on Youtube, either how to install or how to flash BIOS, all the best.