Bad wifi signal! phone dropped, backscreen broken.

Hi!

I've recently dropped the iphone to the ground, and the backplate is shattered. After this I thought it was working, but now i notice that i cant find any wireless networks. At home I need to stand next to my router to get 2 out of 3 on signal. So it works, but its very bad. I've looked for the "metal clipse thingy" at the 4.8mm screw described here:http://guide-images.ifixit.net/igi/Guj1F...

The metal clipse is there, so thats not the problem. And i've seen some guides saying i should clean skrews, and metall connections. But if someone has another idèa or tip im greatfull. Of course i can clean it, but maybe there is a more logic reason(its been dropped). maybe a part to change, or some bad connection on a cable etc.. . ?? ?

Any help would be awsm!

Ty in advance

Greetings Ipwn