Bootloader Fatal Error - GRUB not working

[Şerban S.]

[...] Any other suggestions?

Hello!

To cut the chase...
Windows and Linux never loved too much each other. Mostly Windows...

Now look into your machines info and use the key that pops up the boot menu.
In the boot menu, look for either Windows or Ubuntu/Linux Lite.
This should fix the problem.
As far as I see, there are two bootloaders which on UEFI is OK.
As for using only GRUB to boot both, is more complicated. You need to study the GRUB documentation on UEFI multi boot.
But I suggest you use the POST boot menu instead of digging the whole internet upside down for a solution.

The worst scenaro is... reinstalling everything from scratch.
If this is the last resort, than start with Windows, then when you install Linux Lite 5.0, at boot time, press the key to show the boot menu and from the boot menu, select "UEFI" and the LL stick's name, otherwise your installation will report "successful" but will have trouble with GRUB.
Actually on the same USB you have two different installers: one for BIOS firmware and the second, for UEFI firmware.
Since you have UEFI, you need to select as said above.

I hope you will be able to boot, without reinstalling the whole stuff though...

Anyway, good luck!