I am unsure how to repair my computer.
First, I thought it would be about GRUB2, but I'm not sure anymore.
- access BIOS. Booting from Live USB works fine. (It's EFI)
- access the F12-menu, however it's called. Booting live-usb works fine. (I'm using a Ubuntu Live USB. Same configuration like the computer itself. I guess I used it to install it.)
- access the filesystem from Live USB section. My computer works with lvm.
- not access the grub-menu. I tried these keys: space, shift, esc, c, shift+esc.
- access the grub-menu while booting from live-usb by using shift.
- decide for the very last entry in this menu:
Boot from first hard disk
not boot this successfully. I get this error message:
Booting from local disk… Boot failed: press a key to retry…
So, what's broken? GRUB or the entirely system? What do I need to repair?