Kanger topbox nano help.. again.

So I posted a few weeks ago about battery issues, got a new battery and everything has been okay until a few days ago when my occ 0.15 coils started shorting. The first time it just started flashing 0.00ohms (it would flash 10x if that matters), that was about a week ago. I put a new occ 0.15 coil in and by the first or second day it started flashing 0.00ohms again, this time only 3x. I was out of atomizers so I gave up and left it alone for a couple days.Today I opened the tank to look at the coil, put it back together, hit yes to new atomizer, and fired it expecting to see it flash at me again but it seems to be working fine now? Any ideas what could be going on? Is it okay to keep using that coil now that's working fine?
Also smaller but still annoying problem, when they are working my atomizers only last maybe 3 day before they start to taste burnt. I run it at about 220-240c in TC mode is this normal?