Mesa 7i77 destroyed

Obe of our colleagues just destroyed its mesa 7i77 boar. The 8 channel chips that control the outputs are melted. He is a bit to far away for me to look what was responsible for that.

Has anyobe an idea what could be the fault ?
What kind of problem will cause only theses chips to melt ?

THANK YOU

Greets Rene

I have seen 3 things destroy the output driver chips on a 7i76/7I77

1. Excessive field voltage even for a millisecond (>40V or so) also using a DC
supply with no filter so spikes from the line voltage get forwarded to the field voltage.
The field voltage --> logic power supply is good up to 50V but the output drivers will fail
around 40V

2. Driving inductive loads >60 mA or so with no flyback diode across the load

3. Shorting outputs to line voltage

Thank you for that information !