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Let me preface this by saying I am new to this area of computer science. I will be saying BIOS a lot in this post, but I am not sure if I am using it correctly or if I actually mean UEFI.

I have a 2019 Lenovo Thinkpad T480 and have been running Ubuntu 18.04 with very few issues for a while now. A few days ago, I did a routine update and started experiencing a suite of strange issues (very slow start up, non-responsive keyboard and trackpad, system unable to find sound output devices or wi-fi adaptor).

After some searching around and some trial and error, I found that the culprit could be a bad kernel version (4.15.0-177-generic). Using GRUB to select the previous kernel version seemed to solve all of my issues at once. I found this post that said the way to set an older kernel version as default was to change the value of the variable GRUB_DEFAULT in /etc/default/grub. On my system, it was set to 0 by default, so I changed it to 2, the index of the kernel version as listed in the GRUB menu that had worked previously.

I see now that the answer I followed was 10 years old and things must have changes since then because now my laptop only boots to the BIOS screen and I can't find a way back to the Ubuntu GUI. I cannot access Grub by holding down Shift or Esc during startup. Restarting from the BIOS menu just brings me right back to it, and the only way I can see to shut down is by holding the power button.

Is there anything I can do? I dont know enough about BIOS to risk changing any of the settings without guidance, so any help will be greatly appreciated.

hambrger
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  • (1) Can you get to Grub? (2) You may want to simply consider reinstaling, and backing up any files via a live USB stick (do "Try Ubuntu" on the installer USB, and copy the files to somewhere safe, like cloud storage). Friendly reminder: Don't copy them to the USB, as it fully resets itself (and deletes any files you add) on reboot. Seeing as the current Linux kernel is 5.17, I'd personally reinstall. You could try fixing Grub via a chroot if you know what you are doing, though. – cocomac May 18 '22 at 16:22
  • You could boot a live system from USB meory, CD or DVD, mount your harddisk, revert the change in /etc/default/grub and run update-grub in a chroot environment. See https://askubuntu.com/q/145241/1186757 – Bodo May 18 '22 at 16:25
  • @cocomac I cannot get to Grub -- holding down Shift or Esc do not work – hambrger May 18 '22 at 17:18
  • @Bodo Thank you, that link was exactly what I needed. I was able to revert the change I made, and then I just upgraded to Ubuntu 20.04 to avoid any more messing with the kernel manually – hambrger May 19 '22 at 05:07
  • Does this answer your question? How do I run update-grub from a LiveCD? – karel May 19 '22 at 08:06

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