laptop only works with lid closed

am working on a inspiron 5150 when laptop is first turned on you can see the dell flash screen come up for an instant then it goes away. to make a long diags story short this is what i found.

if i hock the laptop up to an external monitor and keep the lid closed on the laptop then every thing displays fine on the xternal monitor. as soon as i open the lid even just a 1/2 inch the signal to the xternal display goes amber. close the lid or cover whatever and all is just fine again. have done the function f8 key which should switch back and forth between laptop display and external display but it wont display when the cover is open.

i am pretty sure that the display is somehow shorting itself out internally so a new display is most likely needed but dell support also thinks its possible it could also be the system board. this part i dont really agree with them on.

has anyone else seen this type of behavior with a laptop and if so what did you find was the problem. display only or both display and board.

 

It could be a bad ribbon cable for the display.

 

dell wants 180.00 non-refundable and then 260.00 if display and then another 260.00 if the board. so its possible cost to repair would be around 700.00 which definitely aint worth it when you can get a new one for around 900.00.

not much anymore on repairing laptops. finding it harder and harder to see all those tiny screws plus i dont have the componets for laptop repair that i do for desktops. is a shame to just basically trash this machine being its not that old under 2 years old. thats one reason why i insist on a 2 year warranty when i sell a laptop. have seen where if they had a 2 year warranty most times it would come in handy.

thanks whiskeyman