I flashed my Sapphire RX 570 Nitro+ 8GB...I'm now looking into flipping the bios switch.
Disconnect all the cards except for the Sapphire RX 570 Nitro+ 8GB.
Flip the bios switch. Boot into windows. Once booted into windows flip the switch. Flash the bios with the stock bios.
Did you use the Polaris Bios editor (latest version)? If so, did you just click the one click timing button in the bottom right?
Sorry, I'm a bit confused. Do you mean flip the bios switch while it's off, then boot into windows on the second bios, flip the switch back to the one that isn't working while its on and flash it back to stock?
And yes, I used Polaris Bios editor and the one click timing. Does that matter?