Hi Ashutosh,
Go for a small check and then follow the steps,
1. Check all power related connectivity like power port, power cord, adapter and most important the battery.
2. Try replacing the power supply first. If this doesn't work, then try replacing the battery. If, still, nothing, you can either replace the motherboard, which you can purchase online, or take it to a professional to have the power relay replaced.
As per my knowledge this may a power supply issue more than a battery. It is fortunately inexpensive to replace both. The only other thing it could be if replacing these does not work is a bad power relay on the motherboard. If this is the case, you can have this power relay replaced by a professional.