A written explanation won't help. A distribution paid to a non-spouse beneficiary, reported with code 4, is not permitted to be rolled over. TurboTax won't ask the question under these circumstances.
Code G only applies to rollovers to or from a qualified retirement plan like a 401(k).
Was the check that you received and subsequently provided to the new inherited IRA custodian made out to you or was it made out to the receiving IRA?
