Issue with the restarting problem on inspiron 3500 series

In my laptop, I've a issue about 

When um trying to restart or (power on after immediately power off); it will make a led blinking on 2:7, amber:white.

It not permanently solved till when I'm buying that.

I've a temporary resolve for that time, that is holding the power button for 15-20 seconds.

I don't know what to do.