To check voltage across the fuse you need to go line to earth not line to line as that will give 0 volts. This means that you go from one side of the fuse to earth and you should read 12V then do the same on the other side of the fuse and you should still get 12 v. Also checks the integrity of the fuse.
It sounds like the plug to the hazard swithc has been dislodged or not replaced properly. If you pry out the centre air vents with a flat balded screwdriver you can get easy access to all the plugs. Make sure they are all properly connected.
Failing that try another switch either from another ZR/R25 or pop along to a scrappies.