the rule of thumb with people who aren't the technichians don't really know the details. they usualy have a vague knowledge of nokia devices but as this is a completely different device then usual i'd wait for someone who actualy has knowhow to answer my questions.
Have you got anything from extra's devel or extra's testing installed? did you install any custom themes? have you modified any files?
If you answer yes to any of those then thats most likely the problem. Nokia does not cover any 3rd party apps bricking the device so make sure you check that before you give it to their care point technician.