iPad less than one year old. Motherboard fault is this covered by warranty?

Obviously, I suggest that you make an appointment (*) and have your device inspected at an Apple Store or AASP (Apple Authorized Service Provider) among this list:--> https://locate.apple.com/choose-country-region . After checking it out, they'll give you all the available options.

Regards

Giulio

(*) You can do it:

• Online:--> Genius Bar Reservation and Apple Support Options - Apple;
• Contacting a local Apple Store or AASP among the list provided above.

If the device is still covered by warranty, then yes, it should be repaired or replaced for free, unless it has been tampered with.

Regards

Giulio