Reattach magsafe connector on logic board
You may be able to salvage the component; it is possible that you can continue to use it because it's not damaged.

If you can hold it down with tape (just for testing) and it powers up properly, chances are good you can resolder it back on to the logic board.  However, you can't do it with a typical soldering iron.  You will need a reflow gun that blows hot air so you can solder all contacts simultaneously.  

If you don't have the skills to do this or have (or want to invest in) the proper equipment, your best bet is to send it in for repairs.