IRS sent me a check and I don't understand why in the IRS Transcript

I filed my taxes a month ago and on Monday I received a large refund check from the IRS,  I have scoured my 11 page IRS transcript and I can't figure out what/why they changed it.  I used turbo tax and imported almost everything.  I assume I need to amend my return to update my state taxes.  But I don't know what to amend.  You would think the transcript would be more helpful.  I'm waiting for an IRS notice.  Is there a product/person to interpret an IRS Transcript?