strange problem with system

[scooby555t]

ok this afternoon i decide to redo my cooler so took it off took out my cards etc put everythin back on and my system refuses to post any1 got any ideas what it could be i did find a screw under my motherboard i'm thinking that its maybe blown my mobo i just replaced my gfx yesterday this is turning to out to be an expensive month

 

[RJC]

Try removing all components bar the basics and one stick or RAM, double check all power connections and try a CMOS reset.

 

[scooby555t]

tryed all that m8 think its new mobo time i installed a new gfx yesterday it was working fine until today and noticed the fan doesn't spin up so am thinking ive damaged pci e slot but not sure new gfx is a bfg 280 o/c2 as i say everything was working fine yesterday and this morning