Hi and Welcome. My Name is ***** ***** I look forward to assisting you today with your question.
It sounds like you accidentally setup a passcode while setting up the iPad after the update. That is why you are locked out now. You can neither bypass nor find out the password, but there is a way to restore the iPad to working condition. Your only option is to force-restore the iPad to factory settings through iTunes (on your computer) by putting it to DFU (Device Firmware Upgrade) mode, which will erase everything from it.
But if you've 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 DFU 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.
After EXACTLY 8 seconds release the Power button. 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. This will fix the problem.
Note : Put it to DFU Mode while connected to computer and also in DFU Mode your iPad will remain blank and will be unresponsive. It is normal. Timing is critical when you put it to DFU Mode. So keep trying until it goes to DFU Mode. And it will take a while to restore it. Remember, this seems a little difficult but it is very easy.
If you have any difficulty on following the steps above, please let me know and I will walk you through it.
Or if you want, I can remotely connect to your computer and fix the iPad for you while you watch. This is an optional additional service and one time remote session. If you would like me to do this for you, you can accept the remote support offer I sent you. Satisfaction guaranteed. If I couldn't solve your problem, you will get full refund.
Let me know.