To accept return request or not.

Long story short, I sold an $800+ digital item that mentioned in title, description, and a pm to buyer that it is 100% digital. Not paying attention, they bought it anyways. Cancellation was declined because they didn't want to cover the $150 ebay fees that would've come out of my pocket.

Now they're requesting return due to "purchasing wrong item." Should I accept, do a partial and keep some money for my trouble, or keep the full $650 and let it be a learning lesson for them not paying attention?

The title literally started with "DIGITAL." The description was very detailed, the picture looks digital, and I countered their offer with the same amount so that I could attach a message informing them it is a 100% digital item which they totally ignored.