Just for clarity here, the bat tie switch is a hold down switch. The switch must be held down to maintain the tie between the systems as you crank the starter.
I agree with Gerald that the battery is suspect due to the short amount of time you were parked, unless there was some drain on the chassis battery that you did not disclose. They should be good for more than 4 nights under parasitic chassis loads.
The Echo Charger is not my favorite item, made by Xantrex, not my favorite company. I have had two fail and the previous owner had at least one fail. I would check it to make sure that it is working. Check the fuses on it as well as the connections, particularly the ground. Mine was located on the left upper wall of the battery bay.
I prefer the Ultra Trick-L-Start over the Echo Charger, it does about the same job, costs less, is sealed from acid fumes and lasts longer, at least for me.