What action should be performed to successfully process a refund?

To successfully process a refund, the correct action is to press the screen button next to refund and complete the input. This step ensures that the refund transaction is initiated through the payment processing system. Refunds typically require specific input in the system to accurately reflect the transaction in both the merchant's records and the customer's account. By executing this process correctly, the system can track the refund and update the customer's balance accordingly.

Other actions, such as withdrawing cash from the register or disconnecting the payment processor, do not facilitate the refund process through the official payment channels, potentially leading to inaccurate records and financial discrepancies. Informing the customer verbally, while important for customer service, does not complete the necessary steps to execute the financial transaction required to process a refund properly. Thus, performing the action of selecting the refund option on the payment processing system is essential for a successful and accurate refund transaction.