After another firmware update, phone became completely unresponsive. It doesn't show anything on the display (completely nothing). As far as I understand it doesn't send anything on the network (completely nothing), but it initializes it (so if I attach a laptop, it says link is up and down). It doesn't react on any input from the keypad (I even cannot reset to default factory settings). The only sign it's turned on is Headset, Mute and Speaker buttons slowly flashing in sequence. Can anybody advise, how I can solve this? Can I do it myself? Another reset method?