I have a Sony Experia Ultra Z, tried updating the operating system from Kit Kat to Lollipop with Sony PC Companion. Now the phone/pablet will not boot up I have tried resetting through holding red button beside Sim, (which does not work)so pushed and held vol up and power button this vibrated three times but phone will still not boot up. 'Sony Experia' glides across the screen as before but that is it.
Please help