Any idea why my WiFi keeps going down on my early 2011 MacBook Pro?

Basically I got my logic board changed out due to the fact that the my model came with a faulty graphics card (this was done for free at the apple store).

I got my Mac back within a week, everything was working fine and within minutes I noticed the backlight on my keyboard was not turning on. After some research I decided to open my system and noticed that Apple Store had forgotten to plug in the backlight connection to the board, I went ahead to plugged it in and made sure everything else was connected.

Went back to using my system like I always had but then out of nowhere my WiFi signal dropped. I went to the icon and it showed an empty WiFi symbol. When I hovered over it it gave me an option to turn off the WiFi, I did that and then I attempted to turn it back on but it wouldn't give me the option. I then restarted the computer and once it went back it finally gave me the "no hardware installed" symbol.

I decided to shut down the computer, waited about 5 minutes and then started it up. WiFi this time worked fine for about 30 minutes and then did the whole thing again. I tried seeing what the problem was and I concluded that the WiFi signal does not drop as long as I have the bottom cover off, as long as I do not move the system all (any movement makes the WiFi signal drop) and as long as the computer is on a surface that doesn't make it get extra hot.

After doing all this I decided to go to the Apple Store and I told them all of this. to say the least the tech didn't really seem to care about all the research I had done, he took it to the back and came back telling me some things were loose and we tried it at the store and it seemed to work just fine. I took it home binged watched some Netflix and then the next day it dropped the WiFi signal again the same way.

I decided to buy a new WiFi card from IFIXIT. It came in super fast! I plugged it in and seemed to work just fine. Then the next day it started doing all the same things.

At this point I don't know what it could be, a faulty logic board?

Any ideas on what it could be?