Keep console access and a tested backup or rescue environment. Record the exact boot error, disk layout, separate boot/EFI partitions, encryption and RAID arrangement. Confirm whether Secure Boot is enabled and which distribution owns the installed boot files.

1. Observe the boot sequence. Determine whether firmware finds a boot entry, GRUB starts, the kernel loads, or startup fails later while locating the root filesystem. A failure after kernel initialization may need initramfs, storage or fstab repair instead.
2. If an older installed kernel still boots, use it as a controlled diagnostic path and preserve the failed entry for investigation. Do not remove the only known-working kernel.
3. Boot a compatible rescue environment in the firmware mode required by the recovery procedure. Identify and mount the installed root, boot and EFI filesystems correctly before considering a chroot.
4. Follow the current distribution-specific GRUB reinstall procedure for that exact mode. UEFI recovery can involve signed shim/EFI packages and firmware entries; a BIOS disk-install command is not a universal substitute.
5. Rebuild only the configuration or initramfs required by the diagnosed problem. Modern distributions can use forwarding configuration files or Boot Loader Specification entries, so do not overwrite an EFI stub path with an outdated full-configuration command.
6. Check the resulting boot entries and intended root identifiers. Unmount cleanly, return to normal boot and observe the console through a complete startup. Keep rescue access until networking and services are confirmed.

No. Firmware mode, distribution packaging, Secure Boot, architecture and disk layout determine the correct operation. Use the exact supported procedure after identifying those details.

Confirm the expected kernel and root filesystem are active, the machine can complete another planned boot, and Secure Boot remains in its intended state. Check application services and preserve a clear record of the corrected component.

If the error remains, compare the exact stage with the original evidence. Do not repeatedly install GRUB to guessed disks or wipe EFI partitions. For missing storage, encryption or filesystem corruption, switch to the relevant recovery process. Restoring from a tested system backup may be safer than progressively replacing unrelated boot components.

• Inspecting an unbootable Linux server from rescue mode
• Testing a persistent filesystem mount before reboot
• Reading logs from the previous Linux boot
• Testing a Linux server restore before an emergency
• Planning a supported Debian release upgrade

• Debian: Ch03.en
• docs.redhat.com: Assembly Reinstalling Grub Assembly Managing Kernel Command Line Parameters With Uki