The error code " Error 43 " is coming when you GPU stopped working !
You have to fully reinstall your device (GPU) with a clean install maybe .
I found a guide that is updated from this month and hope it helps you get it working again .
Source :
https://www.wepc.com/how-to/how-to-fix-code-43-error/Good Luck and hope it helps to solve your problem and get your 3090 running again.
If this dosnt help you should try the GPU in a other PC , if there is the same problem and it dosnt work there the its something with GPU wrong.