Has the ADF paper chute (cover)/feed guide been opened causing the ScanSnap to stay on even though the ScanSnap has not been used for a certain period of time?
If the ScanSnap is compliant with "ErP Lot6", a regulation for energy saving, the ScanSnap will turn off automatically when it is left unused with the power on for the specified time (default is [After 4 hours]) after it is turned on by opening the ADF paper chute (cover)/feed guide.
You can change the time of the ScanSnap to turn off automatically or change the setting so that it will not turn off automatically.
For details, refer to ScanSnap Help.