Last month my brother got a new phone for his birthday and he's been working on videos to help him improve on the keyboard. The model is a yamaha ypg-235. He one day called me and asked me why this keyboard had a few keys unresponsive. They are all of the E keys and B flat keys. But I saw that when his phone was near the keyboard that it started to flicker on and off. I'm afraid that the radiation from the phone may have gotten into the keyboard's computer software. How do I fix it?