I changed a new coil head and test with a single 18350 trustfire battery again and it worked, working well like it had done the first time I hold it in my hand. Then after hours it stopped working with that coil head, forever, like the other coil heads it did work with.
What a strange story!
This thing is very Chineseeeeeeeeeeeee!
Sigh I thought I have posted this before. This won't work properly with trustfire batts. I have posted this info somewhere in this thread yet people keep making the same mistake like I did. Help yourself and get aw batteries and you will be vaping in glory