VinPuff68.
When you put in the batteries, were they tightly held in place or loose.
I have noticed that the battery on the left sometimes does not make contact with the post.
Try this, With carto removed, put batteries in and take a small screwdriver and place between the let battery and the bottom post and see if the meter lights. Make sure the variable pot is at the half way point to get a reading.
Thank you for your reply

Yes, the contacts were tight. Just no circuit completing..

I sent that one back, and Madvapes promptly sent me a new one.
But I'm having the cut-off issue with 1.7ohm-2.0ohm carts on the new one.
While only pushing about 4.0v-4.5v , and the LED blinks and goes out. No power. Got to on/off it to get it to fire and do the same.
I may try cranking up the power a bit to see if its a heat related issue, or like I read, maybe its a compatibilty issue with the Trustfire batts?
I need to keep reading .. LOL
- Vin