SkyTab Glass is designed to prevent certain payment-related activities when the battery level is too low to ensure the action will be completed.
While the battery is critically low, you will be prevented from:
Taking a Payment
Voiding or Refunding a Ticket
Other activities related to payments
This issue can be easily corrected by placing the SkyTab Glass device on a charger. Even if the battery level is critically low, the device will detect that it is charging and will allow you to complete all payment-related activities.