Well, here is my opinion and a lot of folks here are not going to like it.
When the Istick's (the entire series) became available, everyone was really exited about them.
No surprise there at all. Nice and compact mods with all the bells and whistles at a beyond reasonable price.
And lots of pretty colors as well.
But to get to that price point, those things needed to be mass produced big time to keep the price down.
And as we all know, the Chinese have some severe issues with quality control.
And internally, the Lord only knows what kind of shortcuts they made during the design phase and construction.
Now that these devices have been out on the market for a while (and actually kind of flooding the market) and getting some heavy usage from their owners like all of our mods do (and should be capable of withstanding), wires are starting to come loose inside, covers are starting to come loose as the torx screws work their way out, any glue used in construction starts to deteriorate with age or interiour heat production and who knows what else.
So in conclusion, my guess is that your device has at least one wire that has or is in the process of becoming loose and that may well be your problem.
But again, I don't think these devices were ever intended to last forever or they would have made them to use with standard 18650 batteries in the first place (just my opinion) and your only option may be to try and take the sucker apart and figure out what has gone south.
Or when it dies completely, get another one as they are not that expensive.
Rant over now but I truly do hope you can figure out what is wrong and get it fixed

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