I have been experiencing poor detection with my etrac lately and can't seem to locate any coins below 4 inches. It simply won't give a solid signal for anything but large metal or pop cans below 4 inches >:\ I did a master reset and set the machine up with my usual preferences and made a few patterns. Upon shutting the machine off and walking across the room, the machine turned itself back on and displayed Flat Battery on the screen. Any ideas as to what this means? The battery is the standard rechargeable one that came with the machine and was almost fully charged. I am sending it back in when the season is over , but was wondering what this means?

Thanks