The first thing and most suspect part to cause this issue would be the the water inlet valve. There really isn't too much to test. Bt you need a mete to check for voltage when you first set the machine to start. The place to test is the two wires coming into the water inlet valve (solenoid). This part can stick closed until it gets warm then allow water to flow.
If you are getting power there at least 120 VAC(and the water isn't flowing into the machine) then this part needs replacement.
If there is no voltage there when the machine is started, then you need a new main control board, its a s simple as that on this one;-)
Both of these parts easily replaceable no soldering required.
The best place to get them is: http://www.ransomspares.co.uk/parts/brands/siemens/dishwashers/
But since there are so many different
Please call Ransom Spares: 0844(###) ###-####
Also if you call for the order, they ship same day ;-)
In any case, I will stick with you until this is complete please rate my service kindly.
Also it is the only way I am credited for my time and expertise with you.
Once you rate, I will be notified and will add your question to my priority list so you can reach me anytime until this problem is solved.
Then you can reach me by simply replying to this message anytime.
Thank you and have a Wonderful day!
No additional cost to rate kind;-)