Why will the dishwasher not turn on, drain or do anything? Happened after bang!?

When the drain motor turns on for a Danby dishwasher, it sounds like a buzzer. This is normal

FIRST STEP IS TO CLEAN YOUR SUMP AND DRAIN FILTER AND PUMP CHECK FOR NPOISE AFTER CLEANING

see this causes and fix it. God bless you
Belt, Water Pump Although few dishwashers have a water pump belt, if the dishwasher won't drain there might be a worn or broken water pump belt. After removing the lower kick panel the motor can be seen in the front, the water pump belt is on the bottom of the motor.

Drain Pump If the dishwasher won't drain, the drain pump might be defective. Test the pump motor with an Ohm meter. Drain pumps are not repairable, if it's defective it will need to be replaced.

Drain Impeller The drain impeller is attached to the pump and pushes the water out of the dishwasher, through the drain tube and into the garbage disposer or drain line. If the dishwasher won't drain, the drain impeller might be broken or worn out. Replace both the impeller and seal at the same time.

Drain Solenoid Kit If the dishwasher won't drain, the drain solenoid kit might need to be replaced. The drain solenoid is an actuator that opens a flap to allow the water to drain.
Drain Valve The drain valve can get clogged with debris and should be cleaned out if the dishwasher won't drain. If it seems clear of debris but won't actuate, it will need to be replaced. The drain valve is not repairable.
Pump and Motor Assembly If the dishwasher won't drain, the pump and motor assembly might be defective. If the motor runs during the drain cycle, check for a blockage in the drain line. If the motor won't run during the drain cycle or if it just hums when it should be running, the pump and motor assembly might need to be replaced.

Clogged or Improperly Installed Garbage Disposer If the dishwasher won't drain and the garbage disposer was installed recently, the installer might have forgotten to knock out the drain plug from this disposer. All garbage disposers are sold with a solid plug in the drain tube for situations where a dishwasher isn't connected. However, if the dishwasher is connected, the plug will need to be removed. If the disposer wasn't replaced recently, remove the dishwasher drain hose from the disposer and clean out both the fitting on the disposer and the end of the drain hose. These are the most common places to find an obstruction if the dishwasher won't drain.

Drain Hose If the dishwasher won't drain the drain hose might be clogged. Remove the drain hose from both the dishwasher and the sink drain to clean it out. The most common place for an obstruction is at the garbage disposer.

Check Valve If the dishwasher won't drain the check valve might be stuck closed. The check valve is a small plastic device which prevents water from returning to the dishwasher after it has drained. If the valve gets stuck closed, it will prevent the water from draining. The check valve is the device that the drain hose is attached to on the dishwasher
Check Ball If the dishwasher won't drain the check ball might be stuck. The check ball is a small plastic ball in the check valve which prevents water from returning to the dishwasher after it has drained. If the ball gets stuck, it will prevent the water from draining also. The check valve is the device that the drain hose is attached to on the dishwasher.

Check to make sure it is level (top to bottom and side to side) sometimes the machines are very sensitive to this and will not drain because of it.

hope your dishes are firm in it's seating.

Start with removing the screws in the bottom of the dishwasher and pull out the filter, etc. Clean everything you remove in a sink and soak in white vinegar anything is coated with minerals.
Inspect closely everything you can now see with a flashlight (watch out for broken glass!) Remove any debris found. Reassemble and test if removing any obstructions found.
If problems continue, run a short cycle and listen closely. When the pump should be running, do you hear the sound/hum of the motor turning (but water is not draining?) If yes, replace the pump motor.
If you hear nothing during the cycle when the dishwasher should be draining, the problem is almost certainly a failure of the timer/controller that controls the pump motor.
Good Luck!

I suspect for either of these units that the timer control boards are bad.

It sounds to me like you may have a float switch that is registering water in the unit when you try to start it. If the unit "registers"that there is water in the sump before starting a new cycle, it will try to drain it before starting. The switch is located under the lower acess panel. Sometimes, you can bounce the float (depending on model) inside the unit a couple times and dislodge it. If not, you will have to pull the lower acess panel and check the switch out.

Unplug it and plug it back in after a min. Try to put it threw a rinse spin cycle. Delicate option has a shorter rinse spin time.

See if it suds up, when you hear it trying to drain lift up the drain hose to the wall. It is the gray tube that has the elbow bend, might (should) be hooked to wall. If it isn't moving a good amount of water the machine isn't draining.

It could be the impeller on the motor. The impeller fits over the shaft of the motor and might have split/broken up. That funny noise is probably the shaft spinning inside the damage impeller. Fortunately the impeler is fairly inexpensive and easy to replace. I believe there are one or two parts/covers to remove that are held in by a roughly half dozen torx screws.