If I set the DEPTH knob to the far left, then unplug & plug in the power cable, the green light stays solid. As I turn the knob CW, the green light starts to blink faster and faster. If I back off, the rate does not diminish. If I turn it to the far right, the green light blinks at full rate, and backing off the knob does not do anything.
In short, the DEPTH knob can increase but not decrease.