Get Grub to work again after messing it up OR Wipe out Storage??
by pizzipie from LinuxQuestions.org on (#5871J)
Summary of the problem: I just built a new computer using Western Digital NVMe 500Gb SSD. I installed Ubuntu Mate 18.04.5. I wanted to run Ubuntu Mate 20.04 also so I created a bootable flash-drive and installed it. In running UM 20.04 I tried to change the display resolution and the result was gibberish on the screen. I then tried to boot back up with the Try Me' version on the flash drive but it ran the installed version instead.
What I have Tried: I thought I could remove the partition containing UM 20.04 to force it to boot the Try Me' version so did that with gparted'. Tried booting the flash-drive again and the screen displayed Grub rescue-mode. I didn't have a clue what to do then, so re-created the partition using the old unallocated space. Well that didn't work either, same Grub rescue-mode.
Next Step:I want to turn back the clock and start over with UM 20.04 which has the No. 1 boot preference. I would want the computer to turn on and you have the choice of logging onto UM 18.04 OR UM 20.04.
I think this can be done by tweeking GRUB and I have installed grub-customizer but don't know what to do with it. Totally lost from here on. I messed with GRUB about 20 years ago but am lost on the new stuff.
Short of something else can I:
1: Use gparted to delete the partition for 20.04 and use that space to combine with the partition used for 18.04.5. I'm afraid that 18.04 won't boot then!
2. Use gparted to completely erase or re-partition the SSD to one big partition and start over from scratch?? I trending toward this it I won't make things worse!
Thanks in advance for help in fixing this,
R
What I have Tried: I thought I could remove the partition containing UM 20.04 to force it to boot the Try Me' version so did that with gparted'. Tried booting the flash-drive again and the screen displayed Grub rescue-mode. I didn't have a clue what to do then, so re-created the partition using the old unallocated space. Well that didn't work either, same Grub rescue-mode.
Next Step:I want to turn back the clock and start over with UM 20.04 which has the No. 1 boot preference. I would want the computer to turn on and you have the choice of logging onto UM 18.04 OR UM 20.04.
I think this can be done by tweeking GRUB and I have installed grub-customizer but don't know what to do with it. Totally lost from here on. I messed with GRUB about 20 years ago but am lost on the new stuff.
Short of something else can I:
1: Use gparted to delete the partition for 20.04 and use that space to combine with the partition used for 18.04.5. I'm afraid that 18.04 won't boot then!
2. Use gparted to completely erase or re-partition the SSD to one big partition and start over from scratch?? I trending toward this it I won't make things worse!
Thanks in advance for help in fixing this,
R