Dell E5500 A lock symbol

[685mustang]

My dell e5500 will not turn on it's flashes the A lock key Iv taken batt out for hour an re tried dame thing happens anyone now what this means?

 

[Im Spartacus]

Please try the following it the below link.
http/en.community.dell.com/support-forums/laptop/f/3518/t/19493745