I'm a technician and I noticed this as well. AFTER the wifi card overheats, due to excessive gaming/video streaming, the wifi card has overheated and has not been the same since. It will stop connecting, but I would have to "turn wifi off" for a few minutes and turn it back on and it will work. I don't think the wifi cards are replaceable though... still looking for an answer to that.
My microphone stopped working after I put everything back together very very carefully. I am unsure whether or not I inserted the cable back incorrectly or damaged the cable. I did not find out the mic stopped working until I put everything back together and installed the operating system, so BE EXTRA CAREFUL with the cable! Hope this helps someone!!!
UGH! you have to have a torx screw driver long enough to hit the screw on the bottom right corner where it goes through the motherboard. Just good luck that I had a coworker that had one!!!