There probably aren't all that many failure points in the system that lights up that logo. It's likely either a bad cable connection or more likely a bad couple of lights. Is the problem intermittent? Is the dead section dead all the time or only sometimes?
If it were my amp, I'd open it up and re-seat the cable connecting the logo to whatever power supply it's connected to. Failing that, I'd just contact REVV directly as it's probably a dead group of lights that can't be replaced without replacing the whole logo.