18.04 locks at login, can't edit grub

[borg101]

So I purchased an Acer AN515-53-55G9 and I'm installing 18.04. I've run into a myriad of issues that I managed to troubleshoot thus far. I've finally gotten it installed but upon logging in the system freezes. I know the issue lies with the Nvidia GPU. Unfortunately, the grub menu is set to hidden with timeout=0. And pressing esc only gives me a grub terminal which gives me a list of commands by pressing tab....none of which I recognize. Though I've only been a FT user for ~3 years and haven't had to mess with grub2 much. I tried editing grub from the liveusb but apparently just saving the file doesn't take. So I tried sudo update-grub and I got some error about a cow, which I will add the specific error when I'm home and can view it. Could anyone instruct or point me in the right direction? Every post references dualbooting and such. However I have zero interest in windows or any other software that doesn't embrace Linux/FOSS.

[CatKiller]

The initial boot environment can't read files. It needs to have everything packaged up so that it can be loaded into memory and executed.

What you can do, since you can boot off the live USB, is to use that environment but run things as if you were at the command line of the installed system.

You'd boot into the live USB, mount your / partition, and then use chroot to set that mount point as your pretend / location. Run whatever stuff you need to run, like update-grub or apt-get, then exit and reboot into your normal install.

[oldfred]

COW is copy on write. Or you were trying to edit/update something on the live installer which is not editable.

While I often set grub to 3 sec from default of 10, I would never set it to 0, as then you have the issues you have.

You can chroot into system to make changes as CatKiller suggests.
If UEFI you also have to mount the ESP.
drs305 chroot to purge & reinstall grub2
http://ubuntuforums.org/showthread.php?t=1581099
(http://ubuntuforums.org/showthread.php?t=1581099)
UEFI chroot
http://askubuntu.com/questions/53578/can-i-install-in-uefi-mode-with-the-alternate-installer/57380#57380

You also may be able to use Boot-Repair's advanced mode and its total reinstall of grub. That will reset it back to defaults.

May be best to see details, use ppa version with your live installer or any working install, not older Boot-Repair ISO:
Please copy & paste link to the summary report ( not full report), the auto fix sometimes can create more issues.
https://help.ubuntu.com/community/Boot-Repair

All Acer have needed UEFI updates to latest version from Acer and if SSD firmware updates.
And then Acer has a unique requirement of setting "trust" from within UEFI on ubuntu boot entry.

Acer Trust Settings - details, some now report that then secure boot has to be on to set trust:
https://ubuntuforums.org/showthread.php?t=2297947&p=13369742#post13369742
https://ubuntuforums.org/showthread.php?t=2297947 &
https://ubuntuforums.org/showthread.php?t=2358003

[borg101]

https://help.ubuntu.com/community/Boot-Repair

All Acer have needed UEFI updates to latest version from Acer and if SSD firmware updates.
And then Acer has a unique requirement of setting "trust" from within UEFI on ubuntu boot entry.

Acer Trust Settings - details, some now report that then secure boot has to be on to set trust:
https://ubuntuforums.org/showthread.php?t=2297947&p=13369742#post13369742
https://ubuntuforums.org/showthread.php?t=2297947 &
https://ubuntuforums.org/showthread.php?t=2358003


Thanks for the info. My only question is if all of those links apply. I read most of them on my own but ignored them because they were for fixing problems with dualbooting or solved with bios updates, which is literally the first thing I do after installing any hardware. I don't want to accidentally brick anything.

Also, and I'll look this up now, is there anyway to edit the files on a liveusb so the edited file copies over? I.e. edit etc/grub so the default setting is "nomodeset=0"?

[oldfred]

If booting in UEFI mode from a flash drive, you should be able to edit /boot/grub/grub.cfg.
I always loop mount ISO with grub from my main working install, so I edit that grub which bypasses the grub in the installer.