I make it a policy to never give negative or neutral feedback unless I wasn't completely satisfied with the resolution. Give them the benefit of the doubt; if the refund you got made you happy, no point in pissing all over their feedback. Warn them, explain how & why it wasn't packed properly. These boat anchors need special care, and the average person is not going to have a clue how to do it properly; just assume they did the best they knew how and move on with your life.
I have 100% positive lifetime feedback since they were still called EchoBay; it's hard work and any random psycho asshole can ruin it for no other reason than they're batshit crazy. It sucks to be an upstanding seller in a sea of shit.
If you feel folks need to know that the package arrived damaged, just put down a generic comment to the effect that " Item arrived with shipping damage; vendor made it right right away."
That way folks know to look for more such feedback, and karma is satisfied.
Speaking as a sometimes seller, it is so hard to keep a clean feedback rating on that sh**hole; the whole process is geared to enable outright extortionist tactics from the buyer, and to protect them from any fallout.
Cheers,
mnem
Also, pizza.