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I'm sorry that screen indicates that the firmware of your iPad has been corrupted during the update. Your only option is to force-restore the iPad to factory settings through iTunes by putting it to recovery mode, which will erase everything from it.
But if you had backed up your iPad to iTunes on your computer or iCloud, then you can restore all your data back after restoring your iPad from iTunes/iCloud. You can also redownload all your past purchases for free using the same account.
Follow the steps below to restore your iPad by putting it to recovery Mode.
First download and install latest iTunes on your computer from here : https://www.apple.com/itunes/download/
Then connect the iPad to your computer with the USB Cable.
Open iTunes application on your computer.
On your iPad press and hold the Home button and the Power button at the same time. Continue holding the home button until your iTunes shows a message telling you that it has detected an iPad in recovery mode.
Click OK or Restore
Remember, it may take a while to restore the iPad (the iOS firmware has to be downloaded, you will see the Download button at the top right corner of iTunes screen. Click it to see the time remaining)
Please let me know if that didn't work, so I will continue to help you until we fix the problem.