Stella Ashburne wrote: > I discovered that reinstalling GRUB and then ran update-grub didn't help > at all. The issue still persists. With my limited technical knowledge, the > only way for me to get back the GRUB menu with the blue background is to > reinstall Debian.
I had similar issue on some of the machines. Try with the bios boot from device (some F key). Because you have installed Windows after Debian it could be it has overwritten the EFI partition or the boot order. Once I had to delete the EFI partition and reinstall which solved it, but in your case it might be that the EFI now loads the windows first which might be set in the BIOS or in the EFI. I don't have dual boot, but when I boot from USB stick I have to F9 (HP EliteBook) once so that the bios find the usb and then again F9 which shows the debian boot option.
