You need to take a step wise approach to debug:
1. Make sure the HAT is properly seated.
Orient it so that it is sitting on pins 1-26, here is an illustration on a 40 pin GPIO Raspberry Pi
Use a current version of Raspbian (Compass Linux is deprecated)
Do Not Start amberserver until you confirm that the PiDV is communicating with the Raspberry Pi
Use the test program from
sudo python AMBEtest3.py -i /dev/ttyS0 If this fails, then you may have a hardware problem. On success, then test in foreground (not as daemon, don't use systemctl yet) sudo AMBEserver -i /dev/ttyS0
Watch for errors, and then open a second terminal window and use:
If the ambesocktest works, then you can kill the AMBEserver and restart it with systemctl.
My lab is down at the moment so I am unable to do hands on build and document.
John D. Hays