As I understand it, the fire switch
1/ shuts off fuel
2/ disables ignition
3/ trips gen field
4/ shuts off hyd pump supply
5/ closes air con air bleed
6/ arms fire extinguisher
This means that the CSD/IDG is still connected and the hyd pump has no cooling/lubrication fluid flow.
It is possible to reset the switch I think, but you'd need a real good reason because the hyd pump would almost certainly contaminate the hyd system with metal.