You probably do not need the full motherboard. are you sure that it wasn't just the usb card that was burned? Obviously get rid of the usb cable. BTW, this happened to me also.
X720 Motherboard ( will work with X727)
Edit: sorry its $126 ( Ripoff!) Might as well buy another phone at that price.
Buy the way, we have 4 Leeco phones in our house
You can buy the Leeco x522 for just $107 on Amazon and it has a snapdragon 625 processor and is pretty freaking sweet for just over a hundred bucks. Maybe consider buying that instead of fixing this one.