Disney won't really tell you what happened. When I was there earlier in September, I waited 4 hours outside just waiting for it to open. I know most people would have left and they did, but I had nothing else planned so I stayed and waited. Got to talk to some people.
All we found out was that the CM's that usually work inside the attraction were NOT allowed to go into the building. So, there are a lot of CM's just walking around Pandora that morning. The rumor had it that the big lightning storm that rolled through that night struck the building, so they had to do a complete sweep of the building to make sure it was safe. That was not confirmed, but that could be a possible reason since both attractions are down.
PP, I hope you get a chance to ride Flight of Passage! It is an amazing ride! Also, if it does open up, and you do not have a fastpass, get in line right before the park closes. You won't wait as long as you will during the day.