how to repair uefi boot option

Question

I somehow erased all the boot options in my bios (maybe caused by some operation using super-grub disk). I have tried to fix my grub using boot-repair live-usb. After performing recommended repair and reboot, there is still no boot option in the bios, and I'm brought to the bios setup screen itself everytime I boot.

Complete information about my setup is here.

The whole story started when I found my windows cannot boot (BCD broken error). Then I thought it was a grub issue so I used boot-repair in my linux and performed the recommended repair. Then I found I cannot get into my linux either, only left with a grub> prompt. So I tried super-grub disk and super-grub2 disk live. Then I found I've basically erased all my boot-options in the bios/uefi. Now I've installed another linux (kubuntu) in hope that the new installation could fix the grub, but it didn't. So I finally tried boot-repair live usb and performed the recommended repair, but still no luck. Any idea how to fix this?

Answer 1

finally fixed it with gdisk. not sure which is the crucial step, but after backing up and restoring the uefi header and partition table, upon reboot my linux will try to fix the disk and then fail to mount the efi system partition. At this stage, running gdisk from the rescue command line automatically discovers an erroneous "active" flag associated with the efi system partition. Just letting it fix the flag solves the problem.

It's not a problem with the bios or uefi. I also tried wiping out the efi system partition and reinstalling windows 10. However, that didn't help.