I just got a new motherboard, and the fan screws broke off.?

I bought a new motherboard, LGA Socket 775. I had an old fan and screwed it in to tight, and the screws broke inside of the pegs. I've tried tweezers, small needle-nose pliers, and a wire cutter. NOTHING IS WORKING :,( I want to get some tips how to remove the screws, or replace the backplate. Can any one help with this?