Question Laptop screen issue (haven't found exact issue elsewhere)

[Dragonsbloodmoon]

The laptop was given to me because of this issue. It was barely used. It's a Gateway MD7822u with Windows Vista (yes I know it's kinda old now '07 to be exact, but has pretty good specs and I'd like to install Linux if I can get this fixed). I press the power key and the screen turns on like it should, but after 2-3 seconds it goes black. It works perfectly fine with a TV plugged into the HDMI port. I know the monitor can work properly because working with it I can get it to turn on for a couple seconds then it goes right back off. I've tried taking the battery out and holding the power...etc. with no positive results. I don't think it has anything to do with the OS since it shuts off well before the OS begins to load. {I could possibly be wrong?} BIOS and Windows device manager both claim the ram is good, as well as the driver for the monitor. I have quite a bit of experience building and troubleshooting systems, but this one has me stumped! I've also searched and read everything I can find on the topic. Any sound advice would be greatly appreciated! Thanks!

It seems like some sort of "fail-safe shut off" similar to, but not necessarily a overheat off switch? I may be way off, but that's the best I can relate it to.

 

[hang-the-9]

Backlight may be bad, or the screen itself. If it works with an external screen that is really the only thing it can be.

 

[Dragonsbloodmoon]

Backlight may be bad, or the screen itself. If it works with an external screen that is really the only thing it can be.

It turns on for a few seconds both when I turn the power on and also when I switch it from external screen to internal screen and then shuts off. When it's on it looks fine so I don't understand how it could be a backlight.