As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHORTLY AFTER T/O GEAR DISAGREE WARNING SOUNDS LIKE NOSE GEAR DID NOT RETRACT / SWAPPED LANDING GEAR SELECTOR VALVE IAW CRJ900 AMM 32-32-10-000/400-801. OPERATIONAL TEST OF THE LANDING GEAR EXTENSION/RETRACTION IAW CRJ900 AMM 32-30-00-710-801 GOOD.