What is Smeg?
I can't find anything on model DW1612C

AJ I guess you never watched Red Dwarf.

Smeg (vulgarism), a fictional profanity used in the TV cult space sitcom Red Dwarf.

I actually thought the poster was swearing at his dishwasher but after doing some Googling it turns out that an Italian appliance company has called itself Smeg.

whippetstorm I have never even heard of this company before never mind work on one.
And if AJ has not heard of it then getting any tech info will be difficult but I will try.

If the unit uses a mechanical timer then perhaps that is toast.

If it uses a electronic control board then have you tried removing power from it for a couple minutes to see if the board will reset.

It could be that the start button is always closed. This is a way out in left field guess. Most units that have a control board, monitor the switches and if one of them remains closed for too long then an error occurs.

Try a no heat cycle if you have one. Many units will hang up if the water does not heat to a certain temperature. Though most units will eventually time out and complete the cycle, it just takes a lot longer.
If you think this is a possible cause check the heater for continuity. Also many units have a hi-limit thermostat attached to the bottom of the tub so I would also check for this.

And finally if the unit has soil sensing it could be the sensor is shot or just dirty so the unit keeps trying to clean the dishes but is being told they are still dirty.

Sorry I cannot be of much help. all I can say is Smeg.

OK I tried to find some tech info on this but had no luck.
One thing I did find out is that the actual model number is dwi612c.

I guess they use capitols just to confuse people.