I thought my old Kardia was not working any more, as despite changing the battery twice it seemed dead. This was a pity as my cardiologist was relying on me to record any ' funnies' after my ablation last December which seemed to have been very successful up until a few weeks ago when I had a 2 hour burst of AF.
Then I thought I would try a decent battery instead of the cheap lot I used before, fitted the kind bunnies favour and !!!!! we are back in business.
I know other people have reported problems so thought it worth a mention. Also I have been given a free subscription to Kardia premium as an early adopter....