iPhone 4 - Bad signal after disamble

Hi I have repaired my iPhone 4 and had to resemble the whole iPhone 4.

Atfer putting it together I'm only have a bad signal.

Sometime 1 or 2 bar sometime I'm getting no signal.

What do I have to check?

Antenna seems to be working correctly.

Blue Inductor Coil may be damaged but I tried to bridge it over with solder.

Antenna (on the logic board) is a little bit damaged but the cable fits good.

What do you think where I should look at in order to get the signal back?