Hello Singh, welcome to the forums at Android Central!
I know your pain, that happened to my brother's LG G4 and since it was on my name I had to deal with LG and sending the phone to them.
They didn't give me a hard time, and from the day I sent the phone until I got it back 2.5 weeks had past.
They replaced the motherboard.
Have in mind though that this phone in particular was still within the one year since we got it. Actually, it was just a week or so away from being a year since we got that phone.
But hey, you have nothing to loose asking LG for help.
Good luck, and let us know what happens.