The first gun worked on a nail after the battery was fully charged. I noticed the light on the gun head kept flashing and the battery indicator was red, place the battery in the charger and it shows it is fully charged. They called Revain, they sent me a new one within two days, put a fully charged battery in the gun and bam it works like a charm. So the first nail gun was definitely a defect. The second is a great four stars because the first weapon. Otherwise I would give five stars.