is that the lambo with the spring loaded center pin?
i can't help but think that might be the issue because its so tiny....can you 3 or 5 click the fire button to read ohms on your atomizer? if you five click power does it still give your remaining battery voltage? if the voltage reads, is it below 3.3 volts? is the internal spring on the bottom cap grounding to the metal properly?
basically, when you say you had to fiddle with it, what did you have to fiddle with? because there are multiple things that could go wrong internally, as well as externally, i know if you CAN'T read ohms, then you have an earlier version of the device, and i know a lot of big mods will NOT fire some attached devices with less than a certain resistance as a form of short protection, for example: if the protection setting is 1.5 ohms of resistance, and the attached devices resistance is less than 1.5 ohms, then the device will not fire and may/may not give you an error message depending on what type of circuitry is inside...
also, i know you were using an adapter of sorts, and i don't know if i mentioned it, but a lot of those are adjustable, see if you can turn the center post in that adapter to give a better position...i know your pain in this situation as i commonly adapt 510-801 for my beloved fusion cartos (best cartos around in the world right now imho) and occasionally i need to turn the adapter to adjust depending if the carto fires or not.
also last test, unscrew the device that won't fire one half turn at a time, giving a press of the fire button each time, just to see if it's too tight initially....also check the post on your devices and make sure they have not recessed any....
