Blender won't turn on, but relay buzzes when plugged in.

My blender stopped working a few months ago. I opened it up today after noticing that it buzzed constantly while plugged in. I tried all the buttons and multiple outlets, but it still buzzed, and there was no response to the controls. The power light didn't even come on. I figured it was the motor buzzing, but when I got inside, I disconnected the motor and determined that it was actually the relay on the main circuit board that was buzzing. Any ideas what could cause this? I haven't found any obvious visual problems with the circuit board, though I've tried cleaning it with iso.