I doubt the amp would have any bearing on the bias supply’s. Which you should be able to dial up to where the panels are crackling. Even without a amp hooked up. I’m guessing by the mid point on the adjustment you should hear something. If you don’t hear anything then it sounds bias supply related. As to why both would checkout within a small window of time. I don’t have an explanation for that unless the panels have somehow lost connection or conduction. So what compound was used on these to make the film semiconductive? I’m assuming it is not graphite like my older model.
I’m assuming the bias supply’s are always energized. So do you monitor the a/c line voltage and or run a conditioner? Perhaps for some reason the voltage went high. It might be a good idea to comb thru the house wiring for suspect connections. An example being weird things start happening when a neutral connection goes high resistance.
Best wishes,
DD