Instrument Panel - Ford Fiesta Y Reg?

I recently found that all the dials were at zero including petrol and speedo..(even when the car was moving). I checked the auxilary fuse box and found that one of the fuses (15 - blue one) was blown so i replaced this with a new one. I started the car and everything worked again. However, as soon as I put the car into gear (reverse) it all blew again. Does anybody know what this could be?