No worries, I felt helpless too when I did it, and was looking for information for 12+ hours myself! But I may need to log off soon. I couldn't revisit my screens since I already finalized it, so I am just going from memory... That happens wayyyy before paying.
The screen in question should have the following text:
"About Your State Wages":
"We have transferred a total of $XX,XXX in state wages from your W-2. Is this transferred state wages correct?"
Answer "No". It will lead you to the next screen that asks if you want to transfer only the MA portion. It will affirm you that if you do so, you will no longer be eligible for e-filing. You just need to internally acknowledge that and you can continue as usual. If you check your top left of the screen and look at your refund/owed amount, it should now be the smaller number since you're taxed at the actual wage you earned, not the doubled version.
