If you click the "View" button for a single donation, you're taken to a Donation Detail page. This page shows details about this donation such as amount and fund, as well as the ability to refund the donation.
There's several items on the donation detail page that show specific information about that donation. The left side of the screen should show donor information, and the upper right side of the screen show the fund breakdown. The bottom of the screen shows the result of the donation. Clicking on that donation result will expand to show transactions (how many times the donation was tried - successful donations will only have one, whereas unsuccessful donations might have more). Further clicking on transactions will show the details of the transaction from the bank. This will include any error messages from the bank.
Refunding the donation
To refund or void a donation, click the "Refund" (or "Void", if the transaction has not been settled yet) link at the far right of the donation in the bottom right of the screen.