The first thing is that the water is let in - then it's sloshed around cold then it's heated up and sloshed some more and then the detergent flap is opened. Depending on When in the machine's cycle the Trip happens - you can possibly diagnose the likely fault.
Given what you say it's very probably the heating element - but I just guess.
Your first choice is to repair or replace.
If repair - yourself or an engineer
If replace - where from & how much
Good luck...
Peccavi
February 2010