I ran into a similar issue on my 130 SLT mount and Nextar+ HC.
What I figured is somehow, if you update HC and MC (The CFM seems to update HC first, then MC), that it corrupts whatever it's flashing to the MC's and makes them inoperable.
I had to downgrade the HC using CFM first, then got rid of CFM. I used MCUpdate with older firmware and re-flashed the MC's. So it seems the MC's bootloaders were intact, but whatever was flashed was wrong/corrupted. Then I used CFM to update the MC's to the latest firmware first. Make sure you unclick the HC so it won't update that first! Then once the MC's were flashed, I updated the HC with CFM to the latest as well.
This seems to be a common issue with the order in which they flash and people getting 16/17 error. This was back in September, and I'm disappointed they haven't fixed the issue yet.
I hope this helps someone.
I posted my process here as well: https://www.cloudyni...tes/?p=13713646