cleaned the battery contacts and put in new ones. Now the CM15a shows connected, until I plug it in. Then it disconnects again
Your CM15 issue sounds terminal. If you’re going to continue this route I’d invest in a new one.
Regarding your CM11, I can assure you it works fine with HomeGenie and many other controllers out there, most based around a Raspberry Pi solution but not all, with the aid of a serial to usb cable albeit without the benefit of RF communication.
I wouldn’t invest too much time and energy into AHP. Even Mr T realized this a while back.