Was your replacement a refurbished phone? If so that could be the problem. Refurbished phones arent really fixed properly. They are supposed to, but they obviously are not. my girlfriend had a phone last year, went through 6 refurbished phones that all had more problems than the original. They gave her a new model upgrade, and that phone started having problems. She's now on her 9th refurbushed replacement phone, and every one has problems. Ive read articles online that say phone manufacturers dont really fix any hardware problems when they refurbish a phone. They just clear the memory, load the OS back on, and put a new case/keyboard on them. People may disagree, but with this situation, I find it hard to believe they actually fix them properly.
So, I would take it back and try another replacement. hopefully you will get one that actually works.
