I have a 2005 Great Lakes Penta spa. Balboa 4 button controls and GVS501 board. After draining, cleaning and refilling (actually overflowing), when I connect power the pump continuously cycles on and off. Trouble code " Pr" shows on display. If I hold the jet or turbo buttons, it stops cycling until I release it, then begins cycling again. Where do I start to troubleshoot it? Tia, Jim