Keyer Issue: has my RRC a fault?

[OE7AFT]

The internal keyer of my RRC seems to be faulty. It always generates dashes (or dots if the reverse option is selected) regardless of which paddle (left/right) is being pressed. A factory reset hasn't helped.  Since it was fine till now I rather suspect a hardware failure : is it any way to verify it?
I haven't tried to use the I/O plug yet, I am going to prepare a cable later on.
73 de IZ4AFL

[OE7AFT]

I have tried even the I/O-connector now: grounding #4 works as straight key, #1 generated dots but grounding #2 nothing happens. Is it a confirmation that something is faulty? How can be repaired (my RRC is just a few weeks old).
73