I just replaced the battery inside it. The battery is a combination of three 1.5V Size AA battery welded together in series. When the original battery inside the unit is exhausted, the nail gun will not fire any nail. The LED light will not lit when you press the button. The battery is under the unit next to the led light. You can replaced it with alkaline batteries instead of the original Energizer lithium inside the unit. The original lithium batteries last longer than alkaline. The original lithium batteries are not rechargeable in the unit. There's a russian video on You tube that show the disassembly process under this title " Суперсервис? Не, не слышал! ". IT shows how to open the gun up and shows the battery inside the unit. Self explanatory, no need to under Russian to watch the video.