My daughters GE dishwasher makes a vibrating sound when it is turned on. I tcontinues for about 5 min then goes away (coincident with opening of detergent door).
If the door is opened when it is making the sound, water will be in bottom but none apparently on dishes. After noise stops and door is opened, then dishes will be wet.
It will clean OK but only if not packed as full before vibrating started.
My daughter called this afternoon and said the water level a couple of minutes after the sap dispenser opened was about 2" at the center and at various other points. She also said it did not vibrate in that period before the soap dispensor opened, which is usually does.
It is very hard to say what is wrong with this dishwasher without seeing it. Unfortunately not everything can be diagnosed and fixed remotely. Your daughter probable has to call a pro.