Here is what I do with horses that won't load in, or catch or anything else for that matter. Feed him once he makes it inside the trailer then onces he makes it out. Teach him there is a reward on both ends of the trip.
Not sure what it is you did to get your horse out the last time, but you have already told us it's not the way to do it-so don't do it again. Don't risk scaring your poor animal and permanently causing problems.
Take it easy, plan to take the entire day off and take it slow.