How can i get into the base of my Hotpoint DWF33.Dishwasher?

I have had a problem with this dishwasher in that the heating function does not work. I have been told that it may be down to a tripped relay to the heater element. To access the element i need to get to the base of the machine and i have removed the front base plate but am unable to access the underside of the machine. There seems to be a (keyhole) in the front of the plastic base, with moulded up and down arrows suggesting a special tool needs to be used. Can anyone help please?