Your brother will likely find the following guidance to be helpful is resolving any difficulties with the required AppleID - necessary to facilitate subsequent recovery of the iPad with which you have a problem...
If your device is Activation Locked, this help page will provide most of the information that you’ll need:
https://support.apple.com/en-us/HT201365
If you have forgotten your AppleID or associated password, these can be recovered here:
https://iforgot.apple.com
To recover your credentials, you’ll need access to one of the following:
- Your primary email address mailbox that corresponds with your AppleID
- Any of the secondary/recovery email addresses that should be configured for your AppleID account
- Any of the trusted telephone numbers (fixed line or Cellular/Mobile) that are associated with your AppleID
Unless you AppleID account has not been fully/correctly configured, or has been seriously neglected, recovery of the AppleID and password should not be difficult.
More information about recovery of your AppleID:
https://support.apple.com/en-us/HT201354
More information about recovery of your AppleID password:
https://support.apple.com/en-us/HT201487
After recovering access to the iPad, assuming that you manage to do so, you would be well advised to then prepare it properly for reuse:
What to do before you sell, give away or trade in your iPhone, iPad or iPod touch – Apple Support
I hope this information, insight and guidance proves to be helpful in resolving your problems.