Viper has stopped doing remote start

[mountainbiker]

Off Topic: Viper system in Ford Explorer

Up until yesterday, my Viper 550HF's remote start was working without issue. Yesterday, I disconnected the battery's ground, so I could install a new head unit in the dash.

This morning I tried to remote start. It starts but within a second it shuts itself back off.

The Viper remote still arms/disarms, I have manually started it with the key and driven it without issue, and I have "relearned" the Viper system with the key fob.

I am wondering if I might have forgot to reconnect a cable or may have disconnected one when pushing the head unit in? (I haven't pulled the dash apart again yet as I am waiting on a a new defogger switch. I figured I would look, when I installed the switch.)