I bought my ps3 off ebay and got this demonstration system. I can play games with no problem but all I want is to be able to access the store to buy DLC. How would I do that? I've tried putting the newest firmware update on a USB drive and installing the way and it either says it can't find any available updates or it says the data is corrupted. I've also tried resetting the ps3 and it didn't work so any help would be appreciated.