Quadrax. One envelope stopped to work

I bought a Quadrax module that is still in guarantie and it worked perfectly for one year. One month ago the 4th envelope stopped to work, the green/red light of the cv meter was off. I reinstalled the firmware and it was fixed. Now it happened again. I don’t really know if is better to send it back or if its something that i can fix by my self.
I hope you can help me.

Best to contact support@intellijel.com, our support team will help you sort it out.