If the red button is pressed during a transaction the transaction will be cancelled.
If the transaction requires a signature after the merchant copy is printed, the driver must compare the signature on the back of the card with that of the merchant copy. If it matches, the driver must press ‘yes” for the transaction to be finalised. By pressing “no” you are prompting the terminal to cancel the transaction. Read the prompts carefully to avoid reversing.
If the terminal cannot communicate with the bank the transaction will time out and not go through.