I installed avast for my new android smartphone with mobile security and anti theft. I downloaded a few apps and used it for a day, then had to wait for a few weeks for my new sim card to arrive in the post. Shut it down. When I tried to use it today, it asked me for an emergency number. I didn't know what to do. Then it just gave me a blank screen with android written across it. It is totally unresponsive. I have charged the battery but it does not switch on. What can I do?