If it's going to go in the bin anyhow you could pull it apart and look inside. Nothing to loose. True story- My old Presonus interface had a bad off/on switch which is a push in click/push off click. I had a plastic ink pen laying around
that I robbed the click mechanism from and it fits perfectly in the same hole the Presonus button fit in. Works like a charm.
I realize this is a different kind of thing. If the headphone jack opens the audio channels to the mains it could possibly be bad. Cold solder connections are common. Sometimes running the 1/4" plugs in and out of the jacks will renew corroded connections. They make connection cleaner spray too.............or maybe you were tired of that interface and needed an excuse to buy another one. Here's your chance