I have a similar issue as well as some others and was about to post when I saw this. I can never turn it off when it's heating in session or on demand mode. Also sometimes the rofu logo stays on the screen the same time as the heating info which has me a bit worried. It's been doing that sporadically since the second day I started using it, but the turning it off issue has always been like that.
Also, it seems like I was having good luck with on demand mode in the beginning, but now I can see the temp display drooping when I inhale, and I'm not getting much vapor. Session mode is still working as expected though.
EDIT: I forgot to add the pics. As I mentioned, session mode is still working if you know what I mean. Hehehe
Second edit: I forgot to mention that some times when I try to turn it on, after the fifth tap the logo shows up and it vibrates, but then the screen goes black on nothing happens. Usually the next 5 tap works, but sometimes I have to do it 2-3 times to turn it on. I'm starting to worry their maybe is something wrong with my unit.
I guess I will call them tomorrow.