Folder With Question Mark - Motherboard Issue

Hello

I have a MacBook Air (13-inch, Early 2014) and suddenly it starts showing Folder with Question Mark. I went to B2X in Udaipur and after 3 days the B2X guys are telling me that the Motherboard of my MacBook is not working and i have to replace the Motherboard. Is this Folder Issue is related to Motherboard?

Current status of My MacBook Air is that it is even not showing Green or Orange light when I am connecting the charger to it, even the Folder Icon is not showing and my MacBook is completely dead. Please suggest what I have to do now....

Thanks