Is there any damage visible on the back side? From the initial observation it seems that the “new” damage is limited to a ferrite bead (which is a filter, something like this). Looks like it couldn’t handle the load and melted / exploded.
The good news is that it’s a cheap part (less than a $1) and if you don’t plan to use SC / SP terminals any time soon, you could simply remove it with a soldering iron in order to get back to where things were this morning.
As far as the rest of the circuit, MV10 (which is probably a MOV, overvoltage protector) near the power plug, seems a bit suspicious (not sure what the smudge on top of it is). Would be nice if you could take a close up picture of this part.
An overvoltage could have caused it to degrade and start conducting at lower voltages, or it is possible that 30V AC supply is simply too high to begin with (maybe someone from Rachio could clarify what these MOVs are rated for).
The more I think about it, the more it’s becoming apparent that 30V AC should be considered an overvoltage for this design. MOVs are probably rated for something like 25VAC (like these), which equates to about 35V at the peak voltage. 30V AC on the other hand has a peak voltage of 42V+. If the MOVs on the rachio are anything close to being rated for 25VAC, they would pretty much short anything over 39V.