Perhaps radiation has fried a microcircuit
The chips should be rad hard, but....
On the other hand, perhaps there is another exposure point, and it is sending in something to cause the resets.
My guess is itss going to take an instruction by instruction walk through, and then a fine time analysis of events.
Or perhaps they'll just try it again, to see if the reset occurs again,
and then just upload a systems monitoring program... find the bad circuit, isolate it, reprogram...