Sounds like positive pin is not making a good connection on the mod. Check if the mod 510 still can depress and spring back. Or even try an atty with a longer connection.
9 times out of 10 you should be answering yes, that's what your mod reads right now.
9 times out of 10 you should not do this. It does nothing in power/watts mode. Every time you push that fire button your mod reads the current resistance.