Sounds like a bad cable repair has “blown” a part. If you shine a torch at the screen or turn on computer in dark room, you may be able to see a faint image- this means the backlight is blown(I’m not 100% this trick works) It may be a fuse near the LCD/display cable connection so that no output is sent to LCD. The fact that there is still images seen on another laptop means that the graphics chip is still functioning and the problem is all to do with the LCD and it’s connections.

have a look at these pictures/guide for backlight http://www.tomshardware.com/answers/id-2...