WIFI Antenna 4.8mm Screw (Lost "nut" for it)

I replaced the digitizer on my iphone and after reassembly I have almost no WIFI connectivity (or GPS). I know this is a problem that has already been addressed on this forum but my question is more specific.

When I removed the 4.8 mm screw for the WIFI antenna (the top long screw), when it came out it came out with a "nut" type thing attached to it. Basically it was like a metal nut that was square and would clip onto the board (so it stayed put when you inserted or removed the screw). It was a very small part.

Stupid me, I was like oh #*%!, how the #%^! am I going to get that back in there. Then when the screw "stuck" going back in, like there are threads below (this nut just seems to sit in between, perhaps ground the screw to something - like the motherboard or whatever that small piece connected to.

I have now lost that piece. I am afraid somehow this was the connection that allowed the screw to ground. From what I read this is the screw that grounds the wifi antenna. Which is also curious to me since on the antenna itself, it looks like it is all metal except where this screw is, it seems to be plastic or rubber (meaning it would insulate the screw) which would be weird for a grounding screw.

Does anyone know of the little part I am talking about and what its purpose is? If I lost it, is there anyway to get it or how to install it?

Also, just a side question, is GPS reception tied directly to the WIFI antenna?

Thanks