Here's the process I follow for measuring mod resistance (maybe a bit excessive/redundant, but I wanted to make sure I wasn't leaving any room for error): Wipe down the threads on the 510 connector and the 510 copper Download settingsSet Mod Resistance to 0Upload SettingsTools/Diagnostics/Reboot Device/Soft RebootDownload settings and verify mod resistance is correctly set to 0Open Atomizer AnalyzerCarefully wipe the threads clean on the inside of the mod's 510 and one of these copper 510 tools with thick bounty paper towels, then screw it down carefully and play with it a bit to find the lowest raw resistance I can measure in Atomizer AnalyzerSet Mod Resistance to the lowest value (then I tried lowering it by 0.001 a few times when troubleshooting the shorted error)Tools/Diagnostics/Reboot Device/Soft RebootDownload settings and verify mod resistance is correctly set to new valueThe reason I was testing with the atty resistance locked was because I'm testing with the same profile and material settings as I use successfully with this same atty/coil on my DNA75 BF mod. That mod is 3d printed and regularly has trouble with the 510 coming unscrewed (I believe due to the heat causing the plastic to soften) and the measured resistance of the coil being affected after refilling the bottle if I don't have the feed tube just right or unscrew/screw down the atty again afterwards. Since it's also running on a single 18650 and I regularly have to rotate freshly charged batteries in, locking the atty resistance on that avoids a lot of reliability issues. (That's what's driving me to build this one in an aluminum enclosure.) After my last post, I thought maybe my problem was due to a bad solder joint. The one I questioned the most was between the SS tube that makes up the 510 pin and the brass piece that the wire is soldered to. So, to eliminate that I've tried replacing the FD v4 BF Short 510 with a Varitube BF 510 like I use on my DNA75 squonker. I desoldered the old wires, cleaned the old solder off the 510 pads, cut, stripped, and tinned new 14AWG leads, etc. To connect the 510 lead, I took a small piece of a battery contact, clipped it to an appropriate size, drilled a couple holes in it, and soldered the positive wire to it. This will be clamped between two nuts on the threaded rod Varitube uses in their BF 510 connector. Before even assembling the rest of the 510 I wanted to test my solder connections and see what kind of reading I'd get in atomizer analyzer so far. So, I clamped the positive and negative contacts together and plugged in the 12V power supply then powered it on. Then I connected the USB cable, downloaded settings, and started up atomizer analyzer. Looks like it's not reading what should be shorted contacts. I played with it a bit and it did flash 0.011? at one point before clearing. So now I'm questioning if one of these new solder joints is also bad, or if something might have happened to the 12V power supply I'm running it off of. I'll check the power supply and update when I get a chance to play with it again.