Does the model number of your phone end with the letter U or does it end with U1? If it's simply ends with the letter U it means that it was carrier locked to a specific cell carrier. Even though it may be unlocked, it's still looking for that carrier to perform updates. When your phone boots up, does it give any carrier logo as it's going through the boot process? If it does, you have two options. One you can find a SIM from that carrier and put it in your phone so that it will activate the update process. Or, you can take it to an authorized service center and have them Flash the new software which should cost you less than $100. Otherwise you may want to consider sending it back to amazon.
