Mint 4200 Owner's Manual page 117

Trouble Shooting
Solution
Mint Plus does not detect a NorthStar signal.
Make sure the NorthStar Navigation Cube is in the room and turned on
(a blue light will show in one corner of the Cube).
If Mint Plus is left untouched for more than 5 minutes after it finishes a cleaning cycle,
it goes into sleep mode and the blue indicator lights will appear in sequence. Press
any button to wake it.
The batteries are low. Replace with 2 new C batteries.
The batteries may be dead. Replace with 2 new C batteries.
There may be interference with the NorthStar signal from some televisions and
fluorescent lights.
Make sure the NorthStar Navigation Cube is not placed within 5 feet of
a Plasma or LCD television.
If the Cube is in a room with fluorescent light, move the Cube to an
area without fluorescent light or turn the fluorescent light off.
If Mint Plus has traveled out of range for a while, the NorthStar Navigation Cube may
turn itself off, but when Mint Plus returns it will send a message to the Cube to turn it
back on.
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