Lenovo G570 laptop not starts but induicator lights up for 5-6 seconds?

It was happened before 15 days ago. Laptop doesn't starts up but indicatior lights on for few seconds, after one day it has been starts up without any repair. But for two days same problem araises again. If mother board is dead then how can indicator lights on? So what is the cause and solution?Lenovo G570 laptop not starts but induicator lights up for 5-6 seconds

If battery is completely dead, then it may take a while to recharge enough to start computer.
this might happen. My macbook will not start if the battery is completely discharged. It has taken an hour to get going again! (that is of course even when plugged in.)