Hello, I have an RX 5700XT I'm playing on a big 4K TV 49 inch. I noticed that the bios is green. With Full HD TVs, the picture is normal in the bios. only on the UHD TV is the bios green. I hope it's just the TV and the graphics card is ok.
Wiggle the monitor cable, make sure it's in there or try using a different monitor or different cable.
If that doesn't solve the issue, try to reset your graphics card.