No display on Dell E6510 Led display, hook up external monitor and system comes up properly. I shine a bright light on laptop display and can see a very dim display on the screen. Is this a backlight issue, not sure if this exists on a led display. Any idea on troubleshooting this issue?
Yes, it is a backlight issue and you properly troubleshot the problem.
Since the exterior monitor works, that tells you the computer itself and your graphics solution works. And the fact you can see a dim display when shining a flashlight in there tells you the notebook monitor is getting the video signal.
So you have conclusively determined it IS a backlight problem and that typically means either the inverter or the CCFL itself is bad. Typically both are replaced at the same time. This assumes this notebook uses the older technology inverter/CCFL backlighting and not the newer LED backlighting.
This is a fairly easy and common repair for an experienced technician and parts are typically $50 to $150 (depending on notebook) and labor charges are typically for 1 hour, 2 max.
Virtually ALL monitors are LCD. That is, they have "liquid-crystal display" panels. And all LCD panels require a light source or backlighting. Most TVs are also LCD, though some are plasma and older TVs and monitors were CRT (using a big, heavy picture "tube").
There are two backlighting technologies commonly in use today with LCD monitors. The older uses an inverter and a CCFL (cold-cathode florescent lamp). The newer technology used LEDs (light-emitting diodes).
If you are sure your LCD monitor used LED backlighting, then it is probably the controller card and with the popularity of LED backlit monitors today, the fix may even be cheaper. I would call around to local shops and get a price.