People buy stuff all the time and then return it for all kinds of reasons - didn't like it, realized it they couldn't afford it and etc.
Usually, open box is a return within a very short calendar "window" and the merchandise is new but the box was opened.
Usually, the full original warranty still applies.
We are all brainwashed to one degree or another that buying new is the only way to buy things. I would never buy a new car - the depreciation is a killer - we always buy vehicles around two years old and suffer the consequences of saving a ton of money while enjoying most of the original factory warranty.
We bought our projector at a close out store - big box store shelf unit - had less than 100 hrs on it - almost three years later we are still enjoying it - we paid about 25% of the then current new unit price.
If you must plug it in, turn it on, walk through the menus and then take it hope enjoying the savings.