The open items here refer to any failed or outstanding amount. This is also why the message says, 'Open invoices collection can't be empty'.  Apply this gift to the failed transaction or any future payments.

Option One: Create a New Gift
Remove the future pledge payments (BB710618)

Then, create a new gift schedule with the correct card information.

Option Two: Edit the Existing Gift
  1. Within the contact record, navigate to Financial>Transactions
  2. Click New Gift
  3. Click OK instead of Cancel
  4. Enter the amount received and select a payment type.
  5. Enter any other required information
  6. Mark the radio button for how to apply the payment to the remaining amount
  7. If performing the manual function, expand the pledge nd enter the amount to apply
  8. Click Save