There's a short circuit in the mod 510 connector, or in the atomizer. Doh
.
Try with another atomizer, if you have it, on the same mod and see how it goes.
If that fails try pushing a bit the central pin in the mod connector, so that it moves, then release. Do that a few times, gently.
If all that fails I'm afraid it may be an internal problem with the mod, either the 510 connector or its wiring.