Computer display wont turn on?

[Loves to spooge]

I disassembled my whole computer and cleaned evey part with a cotton swab, then i re-assembled it all back and now it turns on but no display.It powers up alright but there's no beep code when it starts, the monitor shows its got signal.I have tryed 2 diffrent monitors,power supplys,graphics card and onbord graphics, also tryed pulling everything except the cpu and power out.
I think my motherbored is stuffed.

 

[eslfish]

I would think you did reasemble it back the right way.