could be the time delay. E0 seems to imply proper power. it must be getting power to show the E0 status. have you checked the main breaker in you distribution center. if it was tripped you wouldn't be getting power. flip it off to reset it and the flip it back on. if that does not work do you have and can you use a multimeter. measure a/c voltage coming out of the ems. (the voltages it displays are measured from the input side of the ems.) if ok out of the ems then measure at the output side of the power cord. if ok, then measure at the input to the breaker in the distribution panel. there have been many posts about damaged connection where the power cord plugs into the trailer. you're doing nothing wrong. but something is not working. you just have to follow the path the power should take and check each connection until you find the problem.
2015 cardinal model 3825fl
2015 dodge ram 3500 dually