Replaced the display and frame, now I have hardly any cell service

I recently replaced a screen and frame on an S8 and afterwards I had a real difficult time picking up a cell signal, and when it did it was only a bar or so. I have tried swapping out the antenna cables, charge port , nfc and lower speaker with the same result. The replacement is refurbished and I noticed that they had painted over all the little square gold "thingys". Do they have something to do with service antenna? The refurbished replacement screen is the one on the left.