I cannot put back my bed in seat position
Make sure that you are pushing the red handle below the bed on the left side (facing it) towards the trunk and that you did not leave any bag under the bed. It might block the bed system cable.
I cannot put the back seats into bed position
Make sure that there is nothing stuck on the rails that operate the bed movement.
Grab the black handle on the middle of the seats, push it up and drag it towards the front seats.