I have a Pfaff 7530. I used it early one morning, then went back later to use it again. When I turned it on, the screen was blank. I called Pfaff repairman and he said it was the circuit board. I did have it replaced, not cheap to do. I truly love this machine. He also told me, whatever you do, do not get rid of your machine. He also replaced the storage box on the machine, and gave me a new bobbin case. I had replaced the bobbin case, and it didn't have the little thingy that lights up when bobbin is running low. I have never replaced the batteries. Also, make sure you a circuit protector, or unplug when not using.