Relisting a bunch of items past their return date

So, I’m helping clean out my brother’s house, and he had a bit of an Amazon hoarding habit… He has somewhere north of 50 unopened items from Amazon that are all past their return date. Most are unopened.

The items range in price from $20 to $700, including many electronics and computer parts. The whole lot is worth probably $10,000. There are a few heavy items like computer cases. There are also various used electronics which are probably worth another $6,000.

Since almost all of this stuff has a matching Amazon listing, it seems like the logical choice to resell it on there. And, the fees are so much less than selling it on eBay.

Ideally, I’d like to get all of it into Amazon’s FBA warehouse in one batch, as handling the sales and shipping of all of this would practically be a full time job.

So, what I’m wondering: – Are there any services which can take a large amount of assorted Amazon items, and handle the process of getting them sent in to FBA? – Are there any services which would just buy it all, at a discount from what the items retail for? – Are there any general recommendations for how I could DIY the process of getting all of this assorted stuff sent in to FBA myself?*

(*I’ve looked around a fair amount, and most of the advice only covers the case of people who are trying to start a business, or sell large numbers of identical items.)

Any help here would be greatly appreciated!