If that happened could the hand be declared dead?
No. There are pretty much
no situations (short of actually throwing your cards into the muck) where your hand can be ruled dead. In this case, the players may be subject to a penalty, which would only take effect
after the hand is finished.
Back to the OP... as others have mentioned, this is a subject that's come up a bunch of times on here, and the discussion never ends in agreement.
Most of the time checking the hand down is the correct thing to do. Without openly saying that's what you're doing, of course, because doing that is collusion and it's illegal. FWIW, your unspoken agreement to check the hand down is collusion as well, but because you haven't said anything nobody can prove it and penalise you for it.
But to say that you should
always check the hand down in all situations is just plain silly. The most obvious situation where you might want to think about doing something else is this one:
It's on the bubble. You've got a pretty good stack, your opponents are playing super weak-tight because they want to cash, and you're making a killing stealing the blinds and antes. It's actually in your interests for the bubble to go on as long as possible, and therefore you want the short stacks to stay
in. The more chips you accumulate, the better position you'll be in to take down the whole tournament. So why not bet the other players out, even if you only have a weak hand?
To my mind, at least, it's clearly both +chipEV and +$EV for us to keep the short stacks in the game, as opposed to making sure they're eliminated and guaranteeing ourselves a min-cash (which we're pretty certain to claim anyway).