I've had the Lavatube for about a month and today when it was time to change the battery I replaced it with a fully charged battery and hit the button and nothing. I tried this with two more fully charged batteries, (all fairly new and fully charged). The LED read Lo, but the LT measured the battery voltage at 4.1. Then suddnly it started working again, (for about an hour now with no problem). What the heck happened?