Q: I shut off my iPad 2 and now it's asking me to 'slide to upgrade', which doesn't work and won't shut off

Check this Apple support page:

If your iOS 9 device is stuck on Slide to Upgrade - Apple Support

If the steps suggested by Ralph9430 don't work, try the instructions below.

Try to reset your device. This won't delete your data stored on this device.

• Press and hold the Sleep/Wake button
• Press and hold on the Home button
• Keep holding both buttons until the display turns off and back on with Apple logo on it.

As a final step, try the DFU mode:

• Connect your device to your computer using a USB cable.
• Turn off the device.
• Press and hold the Power button for 3 seconds
• Press the Home button while holding the Power button and hold both for 10 seconds.
• Release the Power button, but KEEP HOLDING the Home button.
• After about 15 seconds, iTunes will tell you it has detected a device in Recovery Mode.
• Restore your device

More info here: https://www.theiphonewiki.com/wiki/DFU_Mode

If all these steps don't work, contact Apple and ask for help.

https://www.apple.com/support/ipad/contact/