What does neutral and live both being at +120VRMS above earth imply?
C1 &amp; C2 are surely wrong on your diagram, that metal can is probably a mains filter.

Looks to me like RLY1 or the aux supply that feeds its control signal has failed (A Solid state relay blowing in a surge that takes out the heavy 5V supply is not that much of a surprise), does it have control power when it should?

SSRs do tend to leak a little, even when off which is probably where your 10V or so originates.

Regards, Dan.