Here are your parts
Replacement parts for WHIRLPOOL DU920PFGB0 | AppliancePartsPros.com

Here is the tech sheet
http://www.servicematters.com/d...0Sheet%20-%208066008.pdf

I checked the breaker (it was fine). The only thing I know is that there is power coming to the dishwasher.
How do you know? Just checKing the breaker will not tell you that there is poewr at the plug/hookup.

Based on other online suggestion, I order a new "thermal fuse/wire ($20)" and replaced it.
Nothing. Still dead. Now I am told that it could be the "Electronic control board" ($150+ tax).
Trying Plug & Chug will just cost you extra money. Plug & Chug is plug in a part, try it; plug in another part, try it.

Based on my own research, it could be the door switch too?
Yes but just pushing buttons should not effect the door switches.
Try shutting the off the breaker or unplugging the unit for half an hour or so. Could be that you have confused the microprocessor and locked it up so it needs resetting.
Could be that you locked the control perhaps the LED for it does not work. Try unlocking it see Page 6 in the tech sheet.

I do not know how to use a meter or troubleshoot...
Both are fairly simple so I would like to suggest you give it a shot. Learning to use a meter can be a valuable skill for DIY around the house for anything that uses electricity.

Maybe it is time for a new dishwasher?
Perhaps but if you have the time and the motivation then troubleshooting with a meter is the way to go. Even if it ends up that it makes more sense to replace the unit you have gained knowledge.

I would suggest you purchase a meter.
This will let you check the actual power at the unit and also check many components using resistance with the power off/disconnected which is safer that doing live tests.
You can get a decent digital multimeter for under $20.00. You do not need fancy though it is nice if the leads are a couple feet long.
If it saves ordering one unnecessary part it has paid for itself and you end up owning a useful tool.
Most places will not let you return electrical parts so if you order it, you own it.
A couple things to watch when measuring ohms and continuity
1. Always remove power from the machine otherwise you could blow your meter.
2. Always disconnect at least one side of any device you are checking. This eliminates the possibility of measuring an alternate/parallel circuit path.
3. When checking for closed contacts and continuity use the lowest scale (Usually 200 ohms). Then try higher scales. This scale is 0 to 200 ohms so if the device you are measuring is 300 ohms this scale would show an open circuit which it is not, you are just measuring outside the scale's dynamic range.

There is a good STICKY at the start of this forum about it's use.