Precision 7750, BIOS Auto-Recovery has failed

Try a manual firmware recovery.

https://www.dell.com/support/kbdoc/en-us/000132453/how-to-recover-the-bios-on-a-dell-computer-or-tablet

thanks, i tried but it doesn't work

If so, it sounds like the unknown problem goes deeper that just firmware and will require a replacement system board.  It looks like complete used systems of this model are available for not much more than the cost of a system board, so consider that option as well.

@ejn63​

solved by loading bios from usb