[One Plus One] What are all those pins behind the back cover?

Is it possible to replace/repair these pogo pins (the WiFi one) with a OnePlus One?

Is it possible to reattach the knocked off pogo pin from logic board, in my case Wifi one

Could you tell me if there's a chance to replace the wifi pin with soldering iron?... I broken mine and now wifi+bluetooth is no longer working properly

Everyone asking and wondering about fixing the pins on this and any other phone, the answer is yes. Luckily they're large single connections and aren't located in very populated spots on the board so you can easily just put flux on the single pad(add a tiny flat layer of solder if there isn't much remaining, then add a little flux) then simply place the pin on the pad and place the fine tip of your iron on the base of the pin, heating it up until the solder reflows then gently remove the iron leaving the pin in place to cool. Finally GENTLY clean it with a small amount of alcohol and a qtip.

If you ripped the pad off with the pin you'll have to scrape off some of the solder mask to expose the trace(again, patience is key here, you don't want to be rough and shave off the copper trace as well) in order to make the connection, and probably use a tiny bit of epoxy to hold the pin in position. Tons of old devices have the exact same pins to be salvaged from and work well for practice before the real deal.