Laptop won't boot after fan cleaning/ thermal paste replacement

[tylerbond42]

Hi everybody,

My 4-year-old HP envy laptop (dv6-7245) was frequently crashing due to overheating, so I decided to clean the fan and apply new thermal paste.

I fully disassembled the laptop to access the fan, from which I removed a thick layer of dust. Then I removed the old thermal paste from the CPU heat sink with alcohol and replaced it with new paste.
When reassembled, I connected to the ac adapter and tried to turn it on.

The laptop makes its usual startup noises (fan whirring, hard drive spinning) but the screen is black. Caps lock button is blinking continuously. Tried to reseat RAM and remove static electricity, and disassembled/reassembled 3x more to make sure everything is in its place. Also tried connecting to external display, and same result. Don't know what to do now-- this sounds like one for a tech expert. Any suggestions?

Thanks for helping,

-Tyler

 

[Saga Lout]

The first thing I would try is to connect it to an external monitor if you have one. If you can't do that, I suggest checking the connection of the screen's ribbon cable at the motherboard end.

 

[tylerbond42]

The first thing I would try is to connect it to an external monitor if you have one. If you can't do that, I suggest checking the connection of the screen's ribbon cable at the motherboard end.

Thanks for responding.
I did try connecting to an external monitor, but all it said was "no input detected". And I have looked at the ribbon cable-- it appears to be fine

 

[Saga Lout]

OK - silly suggestion time. Try pressing the Function key that controls the brightness. You may have accidentally turned it right down to total darkness. Here's where I have to admit to having done it myself.

Are you sure you applied new thermal paste to the CPU and not the GPU? Could the latter have been disconnected somehow.