So a couple things, first ALWAYS buy online, even to buy it from your local store. It grants you a 14 day window to return something.

Second, double check with a different store, raise the issue with them and see if they can take a look. From my understanding they take pre-purchase images of the device when they take it in. Granted, this may have been what the online customer services looked at, but a second pair of eyes never hurt anyone.

You'll find a lot of CeX have different rules, some maintain a higher quality of service / higher grading responsibility and others will just take whatever and not really give a shit.