Work gave me a $6,000 treadmill. Having trouble selling. HELP! :)

Hey everyone. During Covid my job gave everyone a very expensive treadmill that I have never opened and is still in box. It is worth over $6000. I have listed it everywhere including craigslist, Facebook marketplace, etc. No bites. I see a lot of big companies like Walmart and Amazon arr selling this treadmill, but obviously I did not purchase it from them. Can anyone think of a way that I can have them take it from me as a return as if I purchased it from them and I’m returning it to them? I would even take the credit to their store, as obviously I would not have any kind of receipt of purchase.

Thanks for the help!