Hey Forum, first time posting here, really hope you can help me out.

I installed a Debian distro on my Dell laptop about a year ago. It was the latest distro at that time.

I spent ages getting the network drivers to work and have subsequently configured a load of software packages inside it.

I Didn't use it for about 6 months. Then it wouldn't boot. No error, just a black screen after POST and it power cycles again.

I almost gave up on it and went to erase the disc with an Ubuntu installer but noticed all the partitions are still intact. This has happened to me many times and its about time I learned how to correct this situation rather than blow away the OS and start again every time it happens.

Can someone please advise me in detail what steps I should take to reinstall / rebuild the GRUB loader? Im pretty good with linux but I have a big knowledge gap when it comes to booting it.

Really appreciate your help.

Is Debian the only OS installed on that computer? If not, what other OS is installed? If there is another OS, does it boot? Do you know if the system is UEFI or Legacy/CSM boot? Is it actually a blank screen or do you see a grub prompt in the upper left (grub>)? Have you read the pages at the Debian site linked below? The first link is for an EFI install and the second is for a Legacy/CSM, make sure you get the correct one. If you have problems post back.

https://wiki.debian.org/GrubEFIReinstall

https://wiki.debian.org/GrubLegacyRecover

Thanks for the quick response. Yep its the only OS. All partitions were removed before I installed Deb.

It has been running on UEFI...

Yep totally black screen. Nothing at all, it just boot loops. It doesn't take long enough during a loop to even try to boot. It just sees nothing. The laptop is fine as the ubuntu installed runs OK and I can get into a USB OS with shell access etc. I just don't know what to do in that shell.

I just having a look around in the BIOS setting now. In boot sequence I see nothing. Completely empty.

There is an option to add boot option. When I click that the add boot option dialogue box contains:

-Boot option name
-File System List
-File Name (with a radio button)

When I click the radio button I see under directories an EFI option which I can browse then in there I see a kali folder and in that is grubx64.efi which I assume is the file it should be pointing at to boot?

So I selected it and BOOM! She boots once more.

This doesn't make any sense. You say it is the only os, but later you say the ubunut installed runs okay.

is the debian install on a usb?

Was this before or after the install? Sometimes this will make things worst.

Do you have to do this every time or does it now boot like it should?

Since its a Dell, you can run the diagnostic test in the BIOS which will check for common hardware errors. Once that is ruled out then other more complex testing can be done.

Not to mention selecting the Kali EFI entry boots something, is it Debian Ubuntu or Kali?

Best way to fix non-booting Debian or Kali is to boot the install medium (net CD or whatever was used to install it), select Graphical rescue mode, go through the questions, select the root partition, accept the suggestion to also mount the EFI partition (since it appears install was done in UEFI mode), then select "Reinstall Grub" and reboot.

Drive may be shot. Hope you have backups. There should always be something in the boot sequence.