No. Atm, there is no working, known, sure way of resetting the C2.
You should, as said, definitely contact the zendesk.
Probably not for a case like yours: insecure experimental beginning of eventual way
There was one user that found an insecure experimental beginning of eventual way to get into the C2. But it seem to me that in the most part of the cases, this can lead to a unusable C2
Flashing the Jolla C2.