As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RECEIVED FLAP FAIL CAUTION ON CLIMB OUT OF ORD WITH FLAPS AT ZERO RETURNED TO ORD FOR UNEVENTFUL LANDING AFTER C/W QRH. NOTE FLAPS WERE ON MEL AT THE TIME. AIRCRAFT REMOVED FROM SERVICE. REPLACED RH BPSU REF AMM 27-51-10 FECU ABORTS BPSU TEST.