A model number may help others help you.

Here are your parts.
Replacement parts for General Electric GSD720P-35BA | AppliancePartsPros.com

If you go to the Sears parts site ans search GSD720P they have part breakdown pictures that may be useful.
Note: The 0 is a zero not a letter o.

The door not opening may be due to detergent residue, I will assume this so that water circulation can be ruled out first.

It could be a low fill situation. Most units fill to just under the heating element.
Also often when it does not fill properly the pump will growl as it is sucking in air.
You can check this by adding a quart or two of hot water after each fill of a cycle. Then if it washes OK low fill is probably your problem. Just be careful to not overfill the unit.

If it is a low fill, shut off the water supply to the unit and remove the water valve. Check/clean the screen filter on the input side of the valve. Do not permanently remove it as it is there to keep crud out of the valve which could hold it open and cause a flood.

Remove the sump cover on the bottom/center of the tub and check in the sump for debris or something wrapped around the chopper.
Be careful as there is often broken glass in the sump.

If the above are not the problem then open up the door so you can see the operation of the dispenser.
Following is a manual which may be useful. It should be close to your unit.
http://appliancedigest.com/index.php?/files/go/804915ec89f972454926534a13e9ad7e/31-3280-clean-design-electro-mechanical-ge-dishwasher-service-manual
You have to join the site to download the manual but it is free and this is a very good site for manuals and other info for the appliance repair DIYer.

Sorry to hear about the flooring problem.

You may want to look around for a dishwasher leak pan. I am not really sure what they call it. It is a plastic pan that fits under the dishwasher and one side has no wall. Then if you get a leak the water is directed out to the front of the machine so it runs onto the kitchen floor. Then at least you know that there is a problem. Often they are not quite the right size (do not cover the water valve) but you can add a small tray made out of a couple layers of tin foil so if it leaks it will also go into the tray. Just be sure to stay away from the valves power connection.

Here is an example
Floor Saver Pan

I regret that this is "closing the barn door after the horse has bolted".