If the system is similar to that on other aircraft (Airbus) then there is no need to switch the GPWS system off, unless for a specific non-routine reason. The fault lights are not that interesting to me on the ground, the off light all the more(thanks for pointing that out A Floor). Again, assuming that the system is similar to what I know.
Anyway, we will have to wait a few months or years for the investigation.
Very sobering pictures.