I got the schematics you sent.
Your dry fire and element failure should not have tripped the internal circuit breaker in the panel, as none of the element current flows thru this breaker (it protects the pump and other non-element wiring.)
You have two contactors (main power, and element power enable) that carry all current that flows thru the element, and these are likely candidates for damage from an over current event. However, I see that both of the contactors have contacts rated at 63A, so it seems that they should have been ok with a short over current event. What is the smallest circuit breaker upstream from your control panel (either in your service panel or your spa panel)?
You could try to isolate where the noise is coming from by using a long necked, plastic funnel as stethoscope. Point the small opening at different components, and hold the funnel end to your ear. Wear thick rubber gloves while doing this.
View attachment 810027 Amazon
Brew on