Good day, ["Viki L"]. Let's get your questions addressed.
Regarding the first one, you'll have to record a refund receipt. This writes off the bank balance. Here's how:
Let's move on to the second question. I'll walk you through with creating an inventory adjustment so you can write off the damaged item. Here's how:
Check this article for more information: How to adjust inventory quantity on hand.
As always, I suggest reaching out to your tax adviser on the best way to handle this.
Feel free to get back to me if you have other concerns.