In some cases the CM820 modem may need to be power cycled to regain functionality.  This can be accomplished by holding down the Reset button.  Pressing the Reset button does not reset the unit to it's factory default setting, but restarts the modem as if the unit was power cycled. This document describes how to power cycle the modem by holding down the Reset button.
NOTE: The CM820 cannot be reset to it's factory default state.
Power Cycle with the Reset Button
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Carefully insert a pointed non-metallic object into the reset button and press on for 5 seconds.
