Unable to log into iCloud account on old device as email address has changed since it was last used

I wish to start reusing an old iPod touch. This has not been powered on in several years.

In the intervening years, I have changed the email address associated with my iCloud account. I also changed the password at the same time.

I am unable to log in to my iCloud account on the old iPod Touch, which is still associated with my old email address – even with the old password.

Logging into my current iCloud account, the Touch is also no longer associated with it.

How should I proceed?