Muck out completely.,
Replace or fix broken hay nets, water drinkers, food troughs, doors etc.
This will let you see any dangers that you could have missed either in the manure or perhaps where the floor has broken. Regularly cleaning stalls is good in case a horse has a scratch, as it could get easily infected in a dirty stall.
, Broken things are dangerous!
Make sure you know how to fix them properly, because a badly fixed item could be more dangerous than something broken.