How do I get out of the rotation of "just two more steps..." and "you're registered?" I can't get past this point.

As it may say on the 2 more steps screen (is there any light gray print?), you likely have forms in your return that have not been finalized and and are not yet available for efiling.    You can't proceed until the forms are released.

Go to the left menu column, and step through the screens in the REVIEW tab.  It should tell you what forms you are waiting on.

Here are some projected dates for various forms:

Federal forms availability dates:
https://ttlc.intuit.com/questions/1908854-forms-availability-table-for-turbotax-federal-products-exc...  

State forms availability dates:
https://ttlc.intuit.com/questions/1908857-state-forms-availability-table-for-turbotax-individual-per...

The IRS will not start processing returns until January 29.  If you efile before then, your return will just sit stockpiled on TurboTax servers until the IRS starts pulling them on January 29 (except for a few test returns pulled early.)   You won't be able to retrieve the return if you notice a mistake, get an additional W-2, 1099, etc.   If you efile at this early point in time and need to change something, you'd have to wait until after January 29 to first find out if your return was accepted or rejected.   If rejected, you could make any change and resubmit.  If accepted, that would require waiting on any refund, then preparing an amended return, which can be a hassle.

Also, if you have EIC (earned income credit, aka EITC) or ACTC (additional child tax credit), the IRS will start processing them on Jan. 29, but will not start releasing those refunds until February 15.  That means people with those types of credits may not start receiving their refunds until around February 27.