Using the automated system, the answer is 'no, you can't'.
All I can suggest is that you speak to Customer Services. (Use the link below to get a callback.)
Explain what has happened and ask them if they can re-open your return using the correct reason.
Ebay rules say this is not possible; personally, I would at least ask.
https://www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)