acer aspire 6930 Laptop Not Turning on

This laptop was working perfectly but i tried it today and it just wont work. At first i thought there was something wrong with the battery or charger but after some tinkering i realised that it turns on when the lid is 3/4 shut. I suspect that the lid sensor is malfunctioning therefore id like someone to please tell me where the sensor is or how to fix this problem