no screw on wifi card!

Hello.

I was disassembling my Vita 3G to change to main board but i got a problem.

On the Guide it said to unscrew the wifi card to remove it ( and after remove main board etc ... ) but there isn't any screw !

To be precise, there is some kind of screw, but it's flat, no cross or anything to grip a screwdriver head on it ! And i can't remove the main board, there is a screw under the wifi card to finally remove it !

There is a way to remove it without damaging anything ?