Received the KitKat upgrade and attempted to install. Phone was at 90+ on battery and I had the phone plugged in during the upgrade. After the install the phone rebooted into the opening screen... stopping at the M logo. It has been sitting like this (with the M logo) for just over 3 hours now. I have attempted to hold the power button down but nothing happens, nor does plugging and unplugging the phone. Any suggestions?