Apple rolled out an updated version of iOS 9.3 for the iPad 2 Thursday afternoon to address a problem where users couldn't activate their tablet after installing. The revised iOS 9.3 installer is build 13E236.
New iOS 9.3 updater fixes iPad 2 bricking issue
iOS 9.3 was released Monday afternoon following the "Let us loop you in" media event where the 4-inch iPhone SE and 9.7-inch iPad Pro were introduced. The update added new features such as Night Shift, but for some devices it also required users to re-authenticate with their iCloud login as part of the activation process—with mixed results.
When The Mac Observer installed iOS 9.3 on a first generation iPad mini and original iPad Air, we were presented with the extra iCloud login request. In both cases, the "welcome" process quit and relaunched, then let us continue activating the devices.
If your iPad 2 is stuck in the post iOS 9.3 unusable state, connect your tablet to iTunes on your computer with its USB sync cable. iTunes should let you install the fixed updater and get you up and running again.