Off 'n' on failed. But I note the little blue LED is actually working, it's just very, very dim (is that the failure mode for a LED?). I think it defeats the object if I have to stand in the shower to see if it's hot yet. Turning the bathroom lights off might work, I suppose. To be honest, it only takes a few second to get hot, the tank is in the next room and the pump directly above. If there's one thing worse than something breaking and costing me money to fix, it's something not quite breaking and still costing me money to fix.