There a little cam inside the caliper thats connected to a lever that in turn connects to the cable. This operates the parking brake.
If the cam over rotates, the piston has to come out to reset it which means ballache getting new seals, bleed nipples and hoping the piston isnt corroded etc
Thats how the brake engineering rep explained it to me anyway!

Looking at those results though, could be the combination of a cable and the caliper tbh. Neither should be expensive to sort