I took apart my phone, and removed, then re-soldered the small battery within the device (only because I accidentally ripped it off the PCB. All you really need to do is lift it up off the contact point, then push it back onto the contact point [as shown in the video
It TEMPORARILY fixed the wifi-and only temporarily
. It lasted three minutes or so, then turned off, and the phone started rebooting again.
Not sure if the battery needs to be replaced or what, but it definitely has something to do with why our WiFi no longer works.
Followed this video:
to figure out which screws needed to be replaced.
Unfortunately I had to drill through the screws (only the silver ones around the outside, not the black screws) to remove the back, because I had no T5 Torx screwdriver, and I stripped the original screws that came with the phone.
MAKE SURE, if you're going to attempt to remove the back, THAT YOU BUY A T5 TORX (or the correct specific size, don't quote me on the fact it's size T5).
Oh, and also, the no sound during calls is related to my hardware. After playing with the speaker, I realized they're both linked.
I've ordered a replacement backing (which includes antenna, speaker, aux jack).