Arrived Saturday night, climbed the fence to get in, and on board we were.
Smell indicated something with the brown water tank was amiss.
Engine wouldn’t start because the only thing the starter motor did was give a simple click sound.
Brown water tank was just over full. After some pumping away and a lot of airing out that should be fine.
Start motor had to be in an inaccessible spot. Didn’t get much further than getting the cover off. Tried again next day, this time with some light tapping on the side and a splash of WD40 and a miracle happened: it turned over.