Haven’t been here in awhile.
Trying to set up an account on a new phone is a dreadful experience. The tutorial for the game just does not seem to end, and there is no easy way to make it stop that I can discern.
Anyways… I lost my entire account and roster. Thousands of days of playing, suddenly gone.
I was hoping to release a few MPQ files I’ve been working on, but with my entire roster gone that’s going to be impossible.
Did your account actually get overwritten or is it just a new account? Can you access your old phone at all? If the data still exists, CS might have something they can do.
On the other hand, now might be exactly the right time to cut ties entirely. MPQ is not a very worthwhile experience, when looked at without the sunk cost looking back. 
Put in a CS ticket and see if they can help you. They might be able to reset your roster to what it looked like earlier. I just got back from a lengthy abscence and I got my account back without problems.
Facebook backup didn’t work, or wasn’t used?
When I changed phones, I just restored my phone backup to new phone and just continued playing immediately. Was your old phone broken? Or did you change OS or something?
You don’t need to play the tutorial all the way through, play the first “node”, hit the gear in the upper left corner, load from fb
After R116 goes live you won’t even have to play that part
Literally just went through this. Even with no back up to Facebook I was able to regain my roster. Put in a ticket, tell them who you are in the game. What your new mobile platform is, and day you last played. They may ask for purchase proofs if you have any. It did take three days, but they came through big for me. Good luck.
If you don’t have a Facebook backup you need to play through the prologue until you reach SHIELD rank 2 and can join a PvE event. CS won’t help you until you get that far.
I had thought that one of the recent updates gave a far earlier chance to restore from Facebook… Thankfully, I’ve not had to test it.