MV component is an MOV, basically a surge protector. Another user had an issue with MV10, you may find his topic (link) relevant to your situation, his protector got fried due to a wrong input voltage.
Good news is that all of the MV## components on the rachio are rated the same. If you have an unused zone (such as MV8 for zone 8, MV7 for zone 7, etc…) you could try replacing the MV10 (main input MOV) with the one from a donor zone.
If you wish to buy new parts, just grab a ruler and see if you can measure the width and length (no need for height) of the burned out part. In the thread I’ve linked to earlier, I’ve made a recommendation for a 1210 part, meaning that the component is 3.2mm by 2.5mm. I want to make sure I’m giving you the right recommendation for an easy replacement.
Cheers,
Gene