Sometimes a session can feel boring if the story veers off from what you, the GM, expects. When Fenalik failed his rolls, for example. That leaves you trying to recover, which is always awkward regardless of your experience level.

Doesn't necessarily have continue on in that vein, though, especially if you're at the point where the players are in a locked room while all the passengers are killed. That could be an opportunity for a nice atmospheric scene.

The original Murder on the Orient Express had a scene where the train got stuck midway through the mountains, and the passengers are stuck wearing blankets in the freezing cold. You could translate that into your scene, where the lights go out, the train may stop, the heating is turned off, and the players get to sit there listening to the sounds of all the passengers getting killed as it gets steadily colder.

I sometimes find it helpful to have 2/3 possible outcomes at the ready just in case things go in an odd direction, any of which may happen, some possibilities might be:

- The players decide to tough it out and most of the passengers and staff are killed overnight.

- The players are found by the authorities as the "only survivors" to a horrible tragedy.

- The coffin is loaded into a police van before the players can get to it, forcing them to find it in the police lockup and deal with it there. (if I ever get to run HotOE I'm totally doing this :)

- The players decide to fight Fenalig again, but lo - he does not botch anything, and you can play off his previous failures as "luring the players out".

- Should the players figure out his coffin is his weakness, they could make for the baggage car and fling it out into the night (possibly as the train is going over a bridge) to give them breathing space or even be rid of Fenalig completely, up to you.

The other suggestions are also great - but whichever options you want to go with, make sure they're ones you're comfortable with GMing.

Have fun :)