Mu 2599LMT-d still works but has a black screen, I can make out faint images.

try taking a small flashlight and hold it to one edge of the screen on an angle and see if you can see a faint image of the screen. if so your backlight is gone.

Depends what you mean by no video.
If the screen is white and washed out, it could be your T-Con board.
If the screen is black, turn the lights off in the room and look for any glow from the screen. If you see glowing, then the backlight is working and your problem is the video/main board.
Shine a flashlight or other strong light on the screen to see if you see any faint images in the screen, if you see images, then your backlight circuit is gone.

Try in a very dark room with set on to look close at screen and or use a flashlight to see if faint images can be seen or not......

Sounds like the backlight has gone. What is the make and model - you may be able to get parts or you may be looking for a salvage one.

Try connecting the laptop to an external monitor first. If this works, you can eliminate the Graphics chip as a source of your problems.
If it fails to work on an external, the graphics chip on the motherboard has possibly gone bad.

If it does work, you have 3 possible problems:

• The VGA cable has been damaged (unlikely)
• The inverter has gone, you can check this by seeing if you can see a faint image on the screen in a darkened room, if you cannot, probably the inverter is at fault and will need replaced
  
• The backlight has gone on the screen, if you CAN see a faint image, then the screen is getting power but the lamps are not lighting, you will need to replace the screen of the laptop.

Check if this will work on an external monitor, if it will, you can point the finger at the following:

• Inverter failed: If you cannot see any image on the screen even a faint one, replace the inverter
• Backlight gone: if you see a faint image on the screen, the screen needs replacing
• Possible failure (unlikely) of the vga cable

If it will NOT work on an external monitor, the graphics chip on the motherboard has failed.

Can you see a faint image on the screen, if so your back light is failing. If you cant even see a faint image and is flickering then the inverter board is faulty and needs to be changed. You can search the internet by doing a google search for the make and model of your monitor and find spares, there should be some good videos on youtube on how to change the inverter.

Check that the monitor is still receiving a signal it could have gone into standby mode.
If not you either have a faulty inverter or the back light has gone, to test this when your computer is on is to check you can still see a faint image on the screen that means the backlight has gone, if not its the inverter.

Does it boot up as bright as it used to be and then go faint or has it recently only been faint?
If it's the latter it sounds as though the lamp has gone. This can be fixed more often than not, but can be a bit expensive.
Is the laptop still under warrenty? If so go back to the manufacturer or if not you should take it into a computer shop to get a quote on fixing it.
Regards, Chris

If you power it on, take a flashlight and shine it on the lcd at and angle and look real close to see if you can see a faint image. If you can, then your backlight in the screen is not working.
Also, you can attatch an external monitor to it, while its off, then power it on and see if it lights the external monitor. Try that and let me know your results.
If you get a picture ok on the external, and you can see a faint image on the lcd using a flashlight, then it could be the backlight inverter board or the bulb itself inside the lcd went out.
If you don't get any picture at all, using an external monitor and can't see a faint image on the lcd using a flashlight, then I would say there's other problems with the laptop itself. Could be a mainboard problem, power issue, etc..