What door would the other bird say leads to Heaven? is what you ask.
If the one you asked is the liar, then he will tell you the door to hell (Cause he will say the opposite of what the truth-teller would say). If you asked the one that always tells the truth, he will tell you the door to hell. (Because he would truthfully tell you the thing that the liar would say, and the liar would tell you the door to hell.) So no matter what, they will tell you which door to not go through. This answers the OP, not the new question.