As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW RETURNED TO GATE DUE TO DUE TO BOTH AIR-CONDITIONING PACKS FAILED AND HAD A LAV SMOKE MESSAGE. THE FLIGHT ATTENDANT REPORTED A STRONG SMOKE SMELL IN LAV AND CABIN AND AN EMERGENCY WAS DECLARED ON THE TAXI WAY AND PEOPLE WERE EVACUATED. MX PERFORMED AN OPS CHECK OF THE RT PACK AND IT CHECKED GOOD. MX DEFERRED THE LEFT PACK.