`CheckifDCMotor` sends a ':' which is not a valid command for AZEQ5/6 mounts, and they return '!1'. This is what I test, exactly '!1' as this is what my AZEQ5 replies. Maybe the AZEQ6 returns another error code and the function returns false. You may test that using picocom if you have it installed: `picocom -b 115200 /dev/ttyUSB0`, hit ':' followed with ctrl-M (there is no echo), and look at the reply. You may close picocom with ctrl-A then ctrl-X. Don't send other commands if you are not sure of what you do (never send ':Q'....).
Concerning EQMod, as we change the indi core library without recompiling it, it may explain the connection issue. But usually this implies a crash when the API has changed and the dynamic loader fails and aborts. Otherwise EQMod should be able to work as usual. I wonder if you actually run the hand compiled binaries. May you try to check if they have been installed in `/usr`:
ls -l `which indiserver indi_eqmod_telescope indi_skywatcherAltAzMount`
If their date are correct, you may try to launch them by hand and connect kstars directly to that indiserver (on localhost port 7624):