I have a similar problem with a lenovo thinkpad T60 , my computer start as always but a couple minutes after turned on ,my screen go black, used to do that just when I connected my power supply. what could I do to fix it.
Is the device actually running and only the display is black? If so try the following.
1. Turn the laptop off.
2. Connect an external monitor to the device.
3. Turn on the external monitor.
4. Turn on the laptop.
Can you see anything on the external screen? If yes, then the attached display is the issue. You would need to first check the ribbon cable that connects the display and if that is not loose, damaged, pinched, etc., then the display may need replacing.
If, however, you can't see anything on the external monitor either, then your graphics card/GPU is probably toast, which means you may need to replace the motherboard.
NOTE: If you laptop is still under warranty, make sure you contact the manufacturer about a repair or replacement rather than opening it up yourself and voiding your warranty.