I recently purchased a second hand Whirlpool Dishwasher and plumbed it in
myself.

It has never worked right from day one, the little green light that is on it
flashes four times then pauses, then flashes four times etc etc. Is this a
fault code? If so what does it mean? I cannot find a manual online or
otherwise and the model number is ADP 4504 and I think it might be a special
number for Comet or something as I cannot find that number on the Whirpool
website.

Anyway if I press the button to start it doesnt seem to do anything, but if
I switch the thing off at the mains for a short time and then back on and
keep the start button pressed in for a few seconds it starts up. It goes
through the whole cycle but the wash quality is quite poor and the remnants
of any water left on the dishes is dirty.

Has anyone got an idea what's wrong with it?

Jay