you done fucked up the secure boot settings I think. I am in no way qualified to help you.

I don't even understand how you can install a different OS. Work off a live USB if you even can.

As far as I understand this is the bit you fucked up. btw, the images in the debian forum post just show "filename1.jpg" as text and don't display. post on !/c/linux4noobs@programming.dev

Step 2: Enroll MOK key for Secure Boot

Debian updates its kernel (minor versions) regularly for security updates and fixes. Without re-building kernel modules every time, DKMS is used, which however needs be signed for secure boot using a machine owner key (MOK).

1. First, run the command below to check if Debian was installed with UEFI boot by running the command below in terminal:

ls /sys/firmware/efi

The command tells to list the /sys/firmware/efi directory content. If it says “No such file or directory”, then you have Debian installed as legacy boot.

2. Next, run command to check if secure boot enabled:

sudo mokutil --sb-state

If both UEFI and secure boot enabled (as the screenshot below shows you), then you need to run commands below one by one to create and enroll MOK key.

3. First, run the command below to manually generate a mok key.

sudo dkms generate_mok

Run sudo apt install dkms if the dkms command not found, and set a password for the key.

4. Next, run command to import the key:

sudo mokutil --import /var/lib/dkms/mok.pub

5. Finally, reboot your computer. At next boot, it should pop-up a screen (see the screenshot below), asking to perform MOK menagement.

There, just choose to Enroll MOK -> continue -> confirm -> enter password (you set when creating the key) -> reboot.

After enabled non-free repository and enrolled MOK key, you may then run the commands below to install NVIDIA driver.

First, install the kernel headers for DKMS:

sudo apt install linux-headers-$(dpkg --print-architecture)