jeremy, set the serial port to 38400 8N1. On boot you should see
PC Engines ALIX.2 v0.99
640 KB Base Memory
261120 KB Extended Memory
If you don’t see this output your issue is not related to ZeroShell.
I’m have a ALIX.2C2 board with ZeroShell 1.0 beta9. Works fine but until Fulvio offers the build environment for download, I have to switch to other distro which are open for 3rd party development.