What is wrong with my dv6-6135DX screen?

[emc2trooper]

HP dv6-6135DX

Was installing Windows updates and then closed the lid. Opened it an hour later and the screen was ultra dim (could only tell the desktop was still up because this particular model has an issue where the HP logo shines through a corner of the screen).

It is black from the moment the laptop powers on.

Performed hard reset. No change.

There is no inverter in this model, so that can't be the problem.

I replaced the screen. Same ultra-dim issue.

It works when plugged into an external monitor.

Windows boots normally and operates fine.

I am completely stumped.

 

[kenrivers]

Does the computer go into a sleep mode when you close the lid? If yes, the problem could be the result of closing the lid while installing updates. Have you closed the lid in the past while installing updates? Is there any way to change the brightness on the screen? Usually there is a button somewhere along the function keys at the top that will allow you to change the screen brightness, usually in combination with another key (Function key? usually denoted by a unique color on the key).