Welcome to ECF and I don't know that mod but you are getting good advice, you pretty much want to try a Hard Reset by pulling the batteries and resetting all the mod's settings to default (hopefully I mean that's the idea and it has worked for me on a couple of occasions) but there's absolutely no reason not to try it.
If that doesn't fix it it's either vape store time (if you have a competent one near you) or like, warranty time (if you aren't out of the warranty period yet, hopefully not, but don't wait around if you're not, because pretty much after a hard reset and that message stays, it's quite likely that it isn't going to go away, ever, and etc.
Best of luck and welcome to ECF.
Anna