Hello, if someone could help me find where a single black wire coming from underneath the main shell goes. it is hanging in the air after a crash, nothing seems to be affected except I have an alarm saying strong interference.
Thanks for helping.

The single black wire you are referring to is an antenna wire.

Hi, thank you for reaching out. We're sorry for the unpleasant experience. In this kind of situation, I'm afraid that you may consider sending the unit in for a proper diagnosis. You can contact our support team to start up a ticket at https://www.dji.com/support. Thank you for your understanding and support!

Was the landing gear slightly demaged ? Looks like the antenna has an issue.

You should have a black wire, a gray wire and a multi-wire ribbon going from the main shell of the drone to the top of the gimbal.  The black and gray wires connect to the main board in the gimbal with little gold connectors and lead to the two 2.4G antennas in the shell.  The wires are prone to being ripped out of the connectors in the gimbal during a crash and, unfortunately, cannot be reattached by us normal mortals.  It requires replacement of the 2.4G antennas inside the shell and then reattaching them to the gimbal board.  There are You Tube videos on how to do this.  It involves some pretty deep disassembly.  The problem you will find is FINDING a pair of the 2.4G internal antennas and when you do find them, not choking on what folks are wanting for them.  They used to sell for around $10.  One guy wanted $60 for a set when I contacted him!  I need a set as well as I too crashed my Phantom 3 Standard.  My roll gimbal motor separated in two pieces so I need a new one of those as well as a new ribbon cable.  Flying without an operable camera is no fun at all.