Static of death. Is the microphone or the sound card the problem?

I have an old Line6 Toneport UX2 and a Studio Projects C1 MkII large diaphragm condenser microphone that I haven’t used in a long time (8yrs+). I just bought my dream guitar and thought I might do some recording.

If I connect an electric guitar to the UX2 it works fine. If I connect the microphone to either one of the two inputs the signal maxes out with static no matter how the gain knobs are set. I get no actual picked up signal from the microphone, or it is drowned by the static. It’s impossible to tell really. I don’t have any other XLR cables or sound cards to try with. The cable looks fine btw.

How do I figure out if it’s the sound card or the mic that is the problem?