to flash your nvidia card first you need to boot with another vga card and blacklist the nvidia driver, edit /etc/default/grub:

GRUB_CMDLINE_LINUX="module.blacklist=nvidia"

then re create grub config:

grub-mkconfig -o /boot/grub/grub.cfg

download nvflash:

wget https://us6-dl.techpowerup.com/files/TPW5J_Rpn_vORfMdP0-XTg/1696398306/nvflash_5.728_linux.zip
unzip nvflash_5.728_linux.zip

set nvflash permissions:

chmod +x nvflash

save bios to file:

./nvflash -b 3070FE-bios-$(date +%F).rom

download bios version:

wget https://www.techpowerup.com/vgabios/231632/NVIDIA.RTX3070.8192.210309.rom

flash bios:

./nvflash NVIDIA.RTX3070.8192.210309.rom

when success with your vgabios flash remove added line from /etc/default/grub and re create grub config:

grub-mkconfig -o /boot/grub/grub.cfg

references

[latest nvflash]

[vgabios collection]

Howto nvflash