You certainly can, but it's unlikely to make a difference if a card has been declined. Your best choice is to have the customer contact their bank to determine the reason for the decline. It's most likely a protection extended by the bank because it's concerned that the card is being used fraudulently. If you choose to manually enter a transaction and it works, please note that you will be paying a higher rate as well as you'll be responsible for any fraud related to the transaction as you aren't utilizing the chip.
https://squareup.com/help/us/en/article/5176-manually-key-in-card-payments-without-the-square-reader
You certainly can, but it's unlikely to make a difference if a card has been declined. Your best choice is to have the customer contact their bank to determine the reason for the decline. It's most likely a protection extended by the bank because it's concerned that the card is being used fraudulently. If you choose to manually enter a transaction and it works, please note that you will be paying a higher rate as well as you'll be responsible for any fraud related to the transaction as you aren't utilizing the chip.
https://squareup.com/help/us/en/article/5176-manually-key-in-card-payments-without-the-square-reader
