The light on the handle of my Cordless nailer is flashing red and green. What does that mean?

The nailer’s electrical system has gone into overload protection. There may be something wrong with the fan motor or the wires going to the fan motor. Remove the battery, fuel and nails. Next remove the cap and grill to inspect the red and black fan motor wires. If the wires are pinched or broken, that may be the problem.