Laptop backlight problem, very weird

[Artus]

Hi!
I have a HP 6730s laptop, the screen had a vertical green line in it so I decided to switch the panel out. I actually had an extra display assembly from another machine(same type). I tried it out but the backlight was not working, the display itself was fine. I installed the CCFL tube from the first previously working panel and it wasn't working... I tried every combination of the cable,inverter,ccfl tube, lcd panel, but the backlight wasn't working. The machine works on an external display. I had a Linux Mint install on the machine, I decided to start it up and as soon as I hit enter in grub to start it, the backlight comes on! It is working flawlessly under linux, even brightness control, but not in the bios or in windows. Anyone have any ideas I could try to fix this? I don't have the funds to get another machine, even second hand, and I need this one with windows for school work.

I tried: 
unplug, take out battery, take out RTC battery, reset bios

reflash bios (would not let me flash a previous bios version, just the current one which is the latest)

 

The machine has an integrated Intel 4500MHD graphics adapter.

 

TLDR: backlight won't work in bios/windows, works flawlessly in Linux Mint. wtf?

[SubTract]

BOOOOM! My mind has been blown!

 

Once your in windows if you turn up the brightness of the display does the backlight turn on?

[Artus]

Nope, the slider disappeared from the power settings page, the keyboard buttons don't work either. Oh, I also tried reinstalling the display driver, nothing.
I'm actually writing this from the Linux install, everything works here... I'm totally dumbfounded about this, never encountered anything like this.

[SubTract]

Dude I'm stumped. Sorry I can't be more help.

[Evil-Erthanu]

Yeah man, that is freakin weird. It's probably unlikely to work, but did you try windows in safe mode? 

[Artus]

I didn't think about safe mode, thanks for the suggestion! Sadly it didn't work.. I let it rest for 2 days now without power, nothing changed. Still working with Mint...