I'm having similar problems that are hard to pinpoint. I recently got a 4-pack of flic buttons. I started using the green one and the blue one. The green seems to be working, but the blue stopped working after just a few uses. It had run out of battery, even though it was brand new, so I took a batter from the black one and the blue one started working again, while the black one stopped. I take it the blue button just drained the battery. It did it again with the new battery. It only worked for a few days, during which I had only pressed it half a dozen times. I'll replace the batter once more with a brand new battery, but then I'm probably going to send the button back for service.
I also have a problem with my buttons showing as "out of range" on my phone, however when I press the green one, it does end up connecting and functioning, though often not on the first try. This is rather annoying. These buttons are supposed to add convenience and save me time, but in many instances they have actually wasted my time. Flic needs to work on reliability.