Q: how can i test it to make sure it works well?
A: well, if it turns on, thats a start. make sure that there is a warnty for the box itself, and your purchase. i wouldnt be surprised if the guy stole 300 bucks from you and gives you a fuked up 360. also see if there are any reviews about the guy's profile. see if his customers are satisfied. (if there is a feature for all of this. there is on eBay) hope this helps and gets best answer