Powerbutton flashes, no power

After my Dex Arm stood still for some weeks I just wanted to start working with the laser module.
When I plug it in and press power button, the button flashes and the arm won’t react or connect to anything. When I plug in the handheld I can use the touchscreen, but the arm does still not react. It does get warm though around the power plug. Has this occured before? Can anyone help me with this?