Either pay a tec to do it, or pack it up and take it back to the store and crack it saying that the console is not new because the screw is striped and you want to replace the hard drive and cant now, and you want a replacement. Don't accept anything other than a replacement, be disgruntled and persistent, maybe make a scene, and they will just want to get rid of you in the end and give you what you want. You shouldn't have a problem because you are inline their policy, they don't know that you did it. Just be careful with the next one, get the correct screwdriver and don't force it. Good Luck.