I Messed Up GRUB2... What a Happy Mistake!

Yesterday, I was using my daughter's desktop computer, which is a Mageia 4/PicarOS dual-boot, when I noticed something that has happended before: after running an update of packages, Mageia changes GRUB2 and erases the entry to boot PicarOS.

I am not very GRUB2 literate.  Last time that it happened, I solved the problem with GRUB Customizer, but it wouldn't help this time.

I tried the Mageia GRUB tool in the Control Center to no avail.

Then I installed the KDE package that lets one configure GRUB2... and that's when I messed up: trying to recover the PicarOS boot entry, I seemed to have installed a useless boot entry on the MBR and the computer, logically, could neither boot PicarOS nor Mageia.

I looked for the Mageia 4 install DVD to run the rescue tool but, since I could not find it, I ran the rescue tools from the Mageia 3 install DVD instead.  It did not work; GRUB2 could not be rescued.

Then I ran a Mageia 3 Live DVD and booted the machine to re-install GRUB2 with Mageia Control Center.  No luck, either, but I found the Mageia 4 install DVD.

Given my little knowledge of GRUB2, my only option at that point was to reinstall the system.  The thing was that I did not want to spend a couple of hours re-configuring the computer.

I ran the installation wizard and it asked me if I wanted a clean install or an upgrade.  I suddenly felt inspired and decided to take a risk.  Normally, I go for a clean install, but I selected UPGRADE instead.

The process lasted less than 5 minutes and Mageia came back to life with a resurrected GRUB2 entry for PicarOS.

But here's the best part. Prior to all this, the computer's Mageia OS had a problem that I had not been able to solve: as ffmpeg could not be updated with the tainted packages, it could not play certain videos for my daughter.

After coming back to life, Mageia told me that no repos were configured. I checked and, sure enough, the install wizard had erased all the repos.  I added them and BINGO!  the missing ffmpeg tainted package was found.

Now my daughter can see her videos again.

Some mistakes bring about happy results after all.