iPad Air 2 can’t able to update software

Start here: https://support.apple.com/en-us/HT201263.

I had this same issue so tried the process outlined in the support article. After iTunes finished updating my iPad it was up to iOS 9.3.2 and said it was fully updated!

I then switched back to my iPad and instead of having the option to 'Download and Install' iOS 11.4.1, the option was just 'Install Now'. But it just spins and spins for hours.

;-(