It can be so many things. Normally on laptops the almost everything is integrated on the MB, even the CPU is soldered to the MB.

I had a Sony Vaio that had a problem on the internal PS. The PS couldn't charge the battery.
Also seen a Dell that had oxidation on the MB due to use nearby the sea. I bought a new MB on eBay and used all the other laptop components.

As BTO just assembled using OEM parts, you may find a new MB for sale