How do I replace the motherboard?

As always, I have to give HP credit for making their service and maintenance manuals available to the general public. Here's where you can find a copy of yours.

HP Pavilion x360 15 Convertible PC Maintenance and Service Guide IMPORTANT! This document is intended for HP authorized service providers only.

System board (that's what their documentation calls the motherboard) replacement instructions start on page 38 (scroll to page 44 in your PDF viewer).

Take lots of pictures as you work and once you're done you can use them to author your very own iFixit guide to that repair! It's easy, fun and will garner the appreciation of the repair community.

Create a new Guide - iFixit

Good luck and let us know how it all turns out