Q: My IpadPro is disabled after downloading the new system

Many users have encountered problems updating their devices, activating them or signing it to their account after iOS 9.3 update. Apple is aware of the problem and is working on a fix.

Take a look at these articles to get additional information on the issue or fit it:

If you can't activate your iPhone, iPad, or iPod touch after installing iOS 9.3  - Apple Support

Apple halts iOS 9.3 updates for older iDevices due to growing Activation Server Lock issues.