Position the newly purchased LINE IN adapter and wires in place

Using a soldering iron and soldering wire, reattach the red and black wires that extend from the motherboard to their original position on the LINE IN adapter

Use the soldering iron and soldering wire again to reattach the black and blue wires that extend from the battery case to their original position on the LINE IN adapter

The blue wire should attach on the bottom of the battery case and the black wire on the top insertion.

The new LINE IN adapter should now be properly assembled in place with the wires connected to their proper location.