I'm sorry to learn that your client requested a refund for the hours that you manually logged. As a gentle reminder, please know that Upwork Hourly Protection does not cover manually logged hours. If you reject the client's refund request, they have an opportunity to file a dispute for the hours you logged in the last week. Here's more information if your client disputes the hours you logged the previous week.
At the end of the day, and as the owner of your freelancing business, you will decide on how to move forward with this. I do hope that you and your client end your relationship on a positive note.