There could be a few reasons for this problem. It may be that you are pushing down on your tool with too much pressure while sanding, increasing internal heat in the brushless motor, thus heat radiates out through the composite/grip housing to your hand. Applying too much downward pressure will slow your tool down and put a strain on the motor resulting in it getting hot. The smart control board (like a motherboard in a CPU) monitors the excessive heat from the motor and is designed to place the tool in preservation mode, slowing down and eventually shutting down. Keep in mind that your sander is most efficient while maintaining just enough light pressure to control the sander while moving at a rate that allows the sander to do its job without trying to rush. Always select the correct abrasive grit for the job at hand and avoid “driving” ANY sander into a substrate.
Another reason may be that you are using it without a vacuum attached and not removing the gray rubber side vent covers on each side of the tool when doing so. Removing them when using without a vacuum will allow more air flow into the tool so that it operates at normal temperatures. If you do remove them, please keep in mind that they need to be put back in when using your tool with a vacuum to create suction for dust free sanding as well as move air through the body of the sander keeping heat down.
A third reason this could be happening is if you are using your tool with an improper extension cord. With power coming through so much length, you will need to consider an extension cord at a 16 or 14 gauge. Any extension cord that is not up to par will increase the resistance in the electric cord, increasing heat build up. Any sort of plug adaptors can also cause heat in tools.
Keep in mind that it is normal for any and all power tools to become warm during use. Maintaining basic care for your tool is very important as well. Regularly blow out the body of your tool with compressed air to ensure dust does not build up in the motor and bearings (especially if your tool is vacuum compatible). Should your tool begin to overheat from misuse, SurfPrep’s sanders have a built-in shutoff feature to keep your tool from damage. Should this occur, give the tool sufficient time to cool off before restarting it for use. You may need to recalibrate your tool if this occurs.