Having an iPad stuck on the Apple logo, I cannot find a way to shut it down.
When holding down both the top "Power" button and the "Home" buttons, the iPad goes to black screen, but starts again even if I released the buttons when the screen went black.
So, the iPad always comes back to the state showing the back Apple logo on a white screen.
The Apple Logo simply means the iPad is booting. Best to give it time to do so. If after considerable time (20+ mins) it still shows the logo, you can try to implement Recovery mode. You need a PC or Mac with iTunes installed, plus a Lightning cable.
Turn off the iPad. Connect the iPad to the PC/Mac, Launch iTunes, and then hold down the Power and Home buttons until you see a "connect to iTunes" message on the iPad. This will allow you to restore the iPad, reinstalling the OS and apps.