Latitude 5480: Intermittent Screen Backlight issue (under Linux/Seabios/Grub)

Hi everyone,

I'm having some weird issues with my laptops screen backlight. Sometimes it doesn't turn on initially, although, most of the time the issue sorts itself out after some time. I also have never seen it turn off once it was on. I first thought it was a software issue, maybe the backlight not being turned on until some screen refresh re-toggles it. But the issue appeared in the bootloader, bios and the desktop environment itself. The issue also persisted after switching from archlinux to fedora, doing a complete system reinstall.

I'm not sure what to do now, I bought the device from refurbed.de, which does offer a refund/replacement in case of a failure. Or I could go to a repair shop... What do you think, is this a driver issue? Should i try re-flashing my bios?