F480v touch screen doesn't work after simlock removal
 

Hello,

I bought an F480v who's simlock was removed , but now after 2 weeks of usage the phone's touch screen doesn't work anymore.
In the left upper corner of the screen there is now the symbol of the blue light used on police cars.
Can anyone tell me what the probleme is and how to fix it ?
Many thanks in advance !!

Grtzzz...