Hi Lestat,

     More details about your problem would be helpful like:

- What prompted you to replace the display...what were the symptoms and what steps did you take to remedy the problem before you replaced it.

-Where you purchased the replacement display and what type of warranty coverage did it come with.

-Were you able to locate the service manual and perform the installation following the steps indicated.

-Have you toggled the Dell Quickset function key (F1 or Fn+F1 depending on how you have it configured) to activate the internal display.

If this reply was helpful please remember to hit the YES button and if you need further assistance don't hesitate to contact.

hi, thank you for your reply.

-the display will not have the backlight. usually in LED monitor is this the problem

-the display that I tried was new, and I also tried a new flat that connects the motherboard to the display

-I have tried both f1 fn + f1 but that do not work

On external monitor works.