As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FA REPORTS BURNING SMELL IN FIRST CLASS, BOTH PACKS ON, DURING PREFLIGHT / TROUBLESHOT ABNORMAL SMELL IAW CRJ700 FIM 21-22-00-810-806 CAUSE 12. FOUND CHECKS TO BE NORMAL AND NO ABNORMAL SMELLS OR FUMES. SUSPECT BURNING COFFEE IN COFFEE MAKER TO BE ROOT CAUSE.