condenser dryer powers on but trips the electrics when i press start ?

my dryer is a hotpoint aqualitis aqcf852bu (uk) condenser dryer , i have had problems with it for a couple of months blowing cold air so i have had to keep opening the back periodically and resetting the thermostat which is a pain in the bum to say the least , but a few days ago when i pressed start it tripped my electrics and now it turns on (powers on) all but start still trips the electrics i have tried a new fuse i have cleaned all the condenser emptied the drawer emptied the fluff etc etc i have also took the back off the dryer and dried it all out with a hair dryer ive dried it all over with a hair dryer and that still isnt working