On the left side of the toilet (looking at it from the bowl) there should be a hole. I don't remember if it requires an allen wrench or socket, but I found it very hard to operate. Remove the cover in the back and make sure there are no lit lights indicating a problem and requiring a reset. I do not remember the steps to take if one is lit, but it should be in the manual. I, also, found that the micro-switches for opening and closing were the cause of my problems. You had to remove the toilet. Never could get them adjusted correctly and neither could a good RV repair tech. Replaced it finally with an old style foot pedal flush.
Roy Warren