Protection circuitry on mufi kw500--help?

We are not original owners of a mufi kw500. I believe it was 6 years old when we bought it in pristine condition.
Yesterday we had the unit on for 8 hours straight--3 hours sitting waiting for our company to be ready to listen, then 4-5 hours of rock. We played james gang, mumford & sons, wishbone ash, billy cobham, three dog night--our company loves drums and guitars. So it got quite a workout. We had just started deep purple smoke on the water, turned the sound up from 11:00 to 12:30 position-- when we lost the left bank, and the protection circuitry???? Kicked in to lower the volume. The legs went purple.
We turned the system off for a few minutes, then back on. It powered on, then immediately turned purple legs again.
It smelled a little electrical burnish. But not strongly so.
We tried a power up two hours later--same thing--powers on and goes to purple.
Is there a home reset option for the protective circuitry?
Has anyone else run into this? How was it fixed and what did it cost?
Any thoughts would be appreciated.
Obviously the unit isn't under warranty.
We will call the musical fidelity folks for ideas, also.
My husband is a mechanical engineer, and is willing to tackle the issue if we could find some schematics.
Thanks, folks.
Associated gear:
Clearaudio Revolution TT
ARC ph3SE
Tara lab interconnects
MIT z-series power conditioner
Vienna Acoustic Beethoven 4 ohm speakers
MIT 750 series 2 biwired with cvt speaker wires
REL Strata iii subwoofer
Mufi kw500 with RSA duke power conditioner
3 dedicated lines--one for mufi, one for subwoofer,
One for TT-associated equipment.
Rel is run by mufi in 2.1 mode.
5.1 additional equipment was turned off--Yamaha rxv1, Vienna acoustics mozarts speakers w MIT speaker wire and mufi 550ks.
Thanks for helping us!!
Deb