Crypt Puzzle (Maze)

There's really no way to give a straight solution to this puzzle, since
the initial conditions are randomly generated.

I found that it was best to work on one coffin or group of coffins at a time
at the start of the puzzle, until I reached some kind of recognizable pattern
or order to the state of the lids.  Trial and error is the only real
strategy here, at least when you're starting out.

But if the above technique doesn't work for you, there is a definite
solution that will get you to the end.  I should warn you first that the
solution I'm about to give is probably the *least* efficient.  The only
advantage it has is that it's guaranteed to work.  I recommend you try to
get to the end and turn only to these hints when you're hopelessly stuck.

I've numbered the squares in this puzzle a bit differently from the systems
used in other solutions.  The top row is numbered 1-3, left to right, the
middle row is 4-6, and the bottom row is 7-9.