The Neorest has a 3-year warranty, so I guess you are outside that. However, as a first step, until the experts on here weigh in, I would give Toto Tech Support a call at 1-888-295-8134. They are open 8-6 Mon-Friday (Eastern Time) and they are very nice. Maybe they can give you some quick troubleshooting tips right over the phone. There are some troubleshooting tips in the Neorest 500 manual on the Toto web site, but none seem immediately to address your problem. Nevertheless, it never hurts to look. (Go to the product on the web site, then click the downloads and resources tab, then owners manual, then instruction manual, p.38 for troubleshooting. And leave feedback here about how it worked out and what it turned out to be. Folks around here always seem curious about how it turns out, and a lot of folks don't leave follow-ups.