Already Filed - 1099-G Not Reported

My son needs to amend his return because the state never sent the 1099-G and he forgot to include it.  Though he knows the taxes might be "returned" per turbo tax/new law (but he didn't have any withheld and $$ less than $10K) , he still needs to file that form but Turbo Tax WON'T ALLOW IT AT THIS TIME, so, any thoughts?   His 1099-G is only $3840 without any tax withheld.    I don't know how to manually adjust for this either.   How would you handle?  Thank you