Linux GRUB Boot Repair

On power-up my machine drops straight into a GRUB error that reads “unknown filesystem / no such partition.” This began right after I updated my Linux install, so the bootloader itself is now broken, not the disk hardware. I need someone who can: • Diagnose the current GRUB configuration from a live-USB session (fdisk, lsblk, blkid, grub-probe, etc.). • Reinstall or regenerate GRUB (grub-install + update-grub or equivalent) so the system boots normally again. • Verify that all existing partitions remain intact and the default OS starts without manual intervention. Remote work is fine; I can share a live-USB console via AnyDesk or similar, or hand you temporary SSH once we’re in a chroot. The job is complete when the machine restarts to the graphical login screen with no GRUB prompt in sight.