As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ASH FLT 2784 CLT - GSO RETURNED TO THE FIELD DUE TO SMOKE IN THE CABIN. MAINTENANCE FOUND THE APU SIEZED. RAN THE ENGINES TO CLEAR THE CABIN. MX DEFERRED THE APU. 12/15 MAINTENANCE INSPECTED AND FOUND THE APU NOT SIEZED AND WAS FOUND TO BE GYLCOL.