It's important to first verify if there are any jammed or damaged staples inside your tool. If you find any, they need to be removed.
Possible cause:
Jammed or damaged staples.
To safely remove a jammed staple, follow these steps:
Remove the battery from the tool.
Open the magazine and remove all the staples.
Pull up on the Tool-Free Jam Release and unhook the latch.
Lastly, check if the tip of the driving mechanism is in its initial position. If it's not, use a flat head screwdriver to push it back into place. Be sure to remove any bent staples you come across.