Given that you’ve had two Brains stop working, maybe the charger is the problem.
Do you have another MicroUSB charger that you can try? When I travel, I charge my Brain with a MicroUSB charger from an old phone. It charges it successfully, but the lights on the Brain don’t change from red to green when it’s fully charged. I figure that the Brain isn’t being harmed as long as it doesn’t heat up. With another charger I have (actually a brick with MicroUSB cable in this case), the Brain alternates between charging (lights are red) and not charging (lights are peach). That seems like a less desirable situation, so I don’t use that one.