dual boot fails after grub-update

[kahuuna]

I am trying to build system with two ssd's. first ssd for mint 20.2 and second for win7.
I have successfully built both (mbr, legacy bios. NOT UEFI) and all works great. Grub menu comes up, and i can select either mint or win7. All works as it should.

Then...... I modify grub (change splash to see what is going on and 640x480 to 1920x1080), run grub-update and poof... win7 now only will boot into repair mode.

Mint still boots as it should, with the changes reflected. I installed boot-repair and have tried various options but win7 only boots into repair mode.

i have chased my tail on this for many days now and while now i am an expert and speed building win7 from scratch, this is not right.

what am i doing wrong.. Grub based, not life in general, and how do i correct / keep from happening in future.

thanks in advance.

[Jo-con-Ël]

First you need to provide some information as following codes result.

Code: Select all

inxi -Fxxxzr
sudo fdisk -l
sudo blkid
cat /etc/fstab

Changes you are describing in GRUB (resolution) would not affect Windows installed in the other disk. You say you have installed with separate boots in BIOS legacy mode, so you are/were able to boot Windows choosing its drive in boot menu (not grub menu) to be sure the problem is only when choosing Mint drive and then Windows option from GRUB menu.

Using Boot Repair, even from a Linux Mint USB/DVD live as recommended, when no need only complicate things and maybe now you have GRUB installed in both disks MBR. Any way Boot Repair BootInfo summary option will provide all needed to know what happens, but it is worth you boot a Linux Mint Live and run Boot Repair.

Most probable Windows option in GRUB menu is pointing to a wrong Windows loader in a wrong partition (Windows RE tools or Windows Recovery Environment partition?). Copy and paste following code in a terminal and post back url resulting

Code: Select all

cat /boot/grub/grub.cfg | nc termbin.com 9999

If you have the same result booting Windows drive from boot menu and no GRUB menu result (.i.e GRUB is not installed in that MBR) flags in Windows Recovery partition have been changed and now it is unhidden, not hidden as it should be. You can revert those changes in flags with Gparted from your working Mint session.

Install Gparted if it is not installed (apt install gparted) and run pkexec gparted or Menu>Administration>Gparted.

Choose you Windows disk in menu upside on the right and post back an screen shot to be sure.