Cannot load backup (due to changed Apple ID/updated email address)

Question

I have followed the answer provided to Ross202 by Gail from Maine. Unfortunately I fear my problem may be larger.
Objective
Move iCloud-backed up data to new iPhone (old phone "drowned" over holidays)
Context
My original Apple ID was EmailOld. This email address (EmailOld) has been terminated. Unfortunately my iCloud / backup is linked to Apple ID EmailOld (so verifying this is not possible). My new AppleID is EmailNew, and this has been verified. I have tried changing my Apple profile to EmailOld, as suggested by Gail (without the verification email).
Despite following Gail's steps, Apple could not backup my old account. Error message:
"Cannot load backups. There was a problem loading your iCloud Backups. Try again, set up as a new iPhone, or restore from an iTunes backup.
Options
- Try again (*)
- Set up as a new iPhone (**)
- Restore from iTunes (***)"
Troubleshooting steps
(*) Try again repeats same issue.
Apple ID EmailOld: "iCloud Sign in" --> Agree --> "It may take a few minutes to set up your Apple ID" --> Choose backup screen --> takes an age --> above message repeated
AppleID EmailNew: (Update AppleID to EmailNew in My Apple ID) "iCloud Sign in" --> Agree --> "It may take a few minutes to set up your Apple ID" --> "Choose backup" screen, with options --> selection of backups --> but then I either 1) have to enter correct password corresponding with EmailOld (and EmailOld and current password don't match), or 2) get error message above
(**) Set up as a new iPhone (using:
(a) old Apple ID says --> "Could Not Sign In | There was a problem connecting to the server". I have reviewed and checked wifi connection, all in order here. I have tried using new account, same error message,
(b) new Apple ID works. And this is hopeful - the device can detect I have about 10GB data stored on iCloud. However, I cannot agitate this sync from iCloud to my new device
(***) I have logged in to iTunes with Apple ID EmailOld (it works - it even says 17 updates on my apps, however I can't agitate updates). I cannot get a sync going.
My phone requests me to "Connect to iTunes", but I cannot do anything more than this. (I have unplugged and plugged my USB cable many times)
I have also logged in to iTunes with Apple ID EmailNew (it works too). But, again, I cannot connect to iTunes
Possible solutions
Recognition of 10GB iCloud-backed up data on new device (despite the fact that old Apple ID doesn't match new Apple ID)
Any help will be greatly appreciated! 5 hours and counting :/
Thanking the community in advance

Answer 1

Call Apple Care for your country and request help reactivating the Apple ID and resetting the password.