IT is not clear from you post exactly what happened. Did you get an old part back? Or was it just that the part was not in the original packaging? The first situation is a scam and needs further action. The second is just the buyer not knowing your business and why the packaging was important.
Now some advice if I might be so bold? Hope this is taken in the spirit intended - to be educational and helpful.
Rule # 1 - Returns happen.
Rule #2 - Professional sellers plan for returns and work them into their business plan, the rest are just hobby seller.
So selling on eBay one needs to expect and plan for returns. That means setting aside funds to pay for return shipping and funds to offset any losses incurred from items that can not be resold or cannot be resold at the original price. I tax each sale a small percentage and put that aside in a Cookie Jar Fund. Then when a return happens have have funds set aside to pay for the return shipping and off set losses.
Now as far as when fraudulent returns happen - where a buyer returns a rock instead of the item, then I evaluate the time and effort involved in reporting that fraud versus the dollar loss. The steps one can take in that situation involve making a number of reports to various agencies. Most of that can be done on line. If one files those reports and then appeals to eBay with the numbers from those reports, eBay often will issue a courtesy refund. If you need more advice on scam returns, that can be provided.
So it appears as thought that is why eBay asked you to file a police report, a possible scam. Not that the police will do anything . (Expecting people to do for you is a problem I see a lot of when in fact doing for your self is usually the best approach. There are steps one can take in the return process to avoid scams.) But eBay's theory is that it is a crime to file a false police report so takes that as evidence of a fraud, as it were.
But this does not sound like it is the situation you have. It appears that you got your part back, but not the packaging. Did your listing clearing state that items must be returned with the original packaging? Did you note to the buyer when accepting the return that you needed the original packaging back? If there was a serial number of something on the item, why don't you have a photo record of what you shipped? Best I can tell from what was written there is no evidence of a crime here. Might have been a crime, but with no evidence....
So yes, there is a process out there for courtesy refunds from eBay that requires filing police reports, etc. Anyone is free to think this is bizarre and unusual, but it is what is. Learn about returns, how to handle them and the process of dealing with fraud and one will sleep better at night! I know once I got educated enough to banish my ignorance on returns I was able to sleep better. Hope you do too!
