Hot water heater

I have a broken leaky 50 gallon electrical hot water heater I am trying to replace. I’ve got the cold water valve off (perpendicular), the thing is completely disconnected from all power and the drain is hooked up to a hose. I have the hot water turned on in the kitchen and nothing is coming out. It has been 30 minutes and it is still draining. Also the pressure relief valve is draining alot too whenever I open it. Also trying to unscrew any water connections or the expansion tank causes water to spurt out. How do I know if I’m not just running water for no reason. Is there something I’m missing? When i open the drain valve there is slight humming noise and it stops when I close it. I assume thats just the sound of water leaving the tank and not continually filling it?