It took them a week, but Etsy was able to reset my Plaid so I could update by re-entering my bank account number. Great! I put in my number, the same as before, because I quadruple check my digits. And now I have the error message "Account number does not match expected format."
@NanaLetha I tried the 6 zeros, then 2 zeros, then 7 and 8, then 1 zero. Now I've maxed out my attempts and have to wait a while to try again.