Il Mio Problema
Part of a headphone jack was stuck inside the headphone port.
La Mia Riparazione
I ordered a replacement I/O board. Removal and installation was simple.
Il Mio Consiglio
There's a hole on the backside of the headphone port. If there's no physical damage, simply removing the I/O Board and using a small pin allows for removal of any stuck pieces. (Unless you try a super glue trick you read online and end up sealing off the port.)