I heard it was caused by water from the PC galley flooding down onto the E racks because the large fibreglass drain/water barrier was not re-installed after the last C chk.
The top shelf has 4x GCU's, BPCU's, Etc. All A/C gone!
Lucky the inverter lives around the corner in a dryer spot.
It could have been the BIG ONE. It's only a matter of time. What do you think?