I will relate my story with the 540B protection circuitry, for what it is worth.
I had a similar intermittent false triggering of the protection circuitry when I first got my 540B. The protection board had a bit of corrosion from leaking
batteries, so I scrubbed the board with alcohol and a toothbrush. The thing seemed a little better, but often would false trigger for days on end, and then
sometimes would work OK for a while.
I did all the normal replacement of the two transistors, diodes, resistors, etc. to no avail. Finally, I disconnected the board (pain in the ass) and removed it.
I took out the two transistors and a few other parts and put an ohmmeter across various traces. I was getting readings like 250K across two traces
that were totally isolated (no components attached).
At that point, I figured what the hell - I couldn't make it worse, so I scrubbed the board with steel wool and muriatic acid. And I mean I really scrubbed
and scrubbed. Rinsed the board off with water, let it dry, reinstalled the parts I had pulled, and put the board back into the 540B.
The protection circuitry has been operating flawlessly now for over 6 months.