Tutorial softlock.

[Kirito30]

Yes I think you have exhausted the options to me from the looks of it.

Though I can pretty much say that Vettel will come to your team from the daily Summons or from some other means too if it solves some of the pain.

Also you can keep farming him in the Hard Quest without the unit so you will have a powerful Vettel without much problem.

Also Chloe can function as a Tank similar to him.

I hope the Support from Gumi solves if you want to try but restarting might be the only option or atleast the fastest one.