I know you said the dash lights came on momentarily but did you check you battery disconnect down by the key? I know I blame everything on my 5 year old but that has been hit by accident and you will have a dead key when you go to turn it on.
I had something similar happen one time. Stopped, put my flashers on, and shut the key off. I left to take care of something and when I came back I turned the flashers off right before I went to start the bus. I turned the key and nothing (all dash lights were on like usual) happened. I had to turn the flashers back on for the bus to start THEN turn them off. I thought that was odd but just made a mental note to do the procedure in reverse. Not sure why that happpened.
Also, Id check the rear grey box above the engine in the engine bay and do a visual with the solenoid(s) and make sure the rear start is not engaged (not sure how that could happen but Im just trying to help). A solenoid could look burned, etc. You may need a multimeter, etc. to check further.
Maybe see if the bus will start on the rear button?
Patrick Collins
Stuart, FL
2001 Prevost Liberty Lady Classic #466
patrick@libertycoach.com