Preferably a 2 wheel dolly with stair rollers. IF you don't have a friend, a couple of ratchet straps (to hold the tank on the dolly) and a come-along (to pull the assembly up the stairs) will work pretty well.

Alternatively, since it has failed, you don't need to worry about getting it up the stairs in one piece. So go after it with a sawzall and work out some hostility.