Hello, 
 
I took apart my Dell Studio 1557 to clean it (and not for the first time), but this time after I put everything back the laptop won't turn on.  
 
I have this laptop since 2009 and didn't have any problems before. 
 
When I press the power button, I can hear that CD-ROM, HDD start to work, Also the CPU and Graphic card getting warm, but there is nothing on the screen (remains black) and fan doesn't start. 
 
I figured out that it's probably some problem with the motherboard and ordered a new one on eBay (exactly the same part), but to my surprise after changing the board I ended up in exactly the same situation as before (no screen and fan; CD-ROM, HDD, CPU, GPU work). 

The only noticable diffence after changing the board is that with old board after pressing the power button there was light around it (as it should), and there is  none with the new one.

Can it be that I got a faulty board on eBay and should request a replacement? (seems strange consdering almost the same bahavior after the change).

I tried to drain the static charge, and also to connect an external monitor but it didn't help. 

I'd appriciate any help and suggestions. Thanks.