Fix Fault Sigmatel

my sigmatel mobile is autometically switch off now itsa not switch on what.but torch light is in working condition

For last week in the above mobile phone Sim 2 is not activating my sim and shows "Invalid Sim" instead of running another sim. I have no repairing shop for chinese mobiles in my area. please help me t ... more

my sigmatel mobile is autometically switch off now itsa not switch on what