Sony have released a firmware update for the PXW-FS7 that includes a fix for a problem that can in very rare situations cause the footage to be over exposed. There have been very few reported cases of the problem and it only occurs in the CineEI mode after a camera re-start. The new firmware update has been released to prevent it happening. It’s recommended that you update you camera to this new version, version 4.1.
You can download it from here: https://www.sony.co.uk/pro/support/software/SET_BPE-SS-1238/70