Hi and welcome to ECF
Definitely do not soak in water unless you want to destroy your battery. Electronics+water=bad (also it would do nothing to help unscrew the
tank). If you have a rubber jar opener, rubber glove or if nothing else a wad of saran wrap - take it and wrap it around your atomizer/
tank/whatever the heck is stuck on top and then use pliers you may have some luck.
In the future - these should only be *just* tight enough to stay together. You can compress your firing pin amongst other issues when you put them together this tightly. Put on the atomizer and turn until its *just* snug and STOP. You will be glad about later
