As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MECHANICAL LANDING GEAR SYSTEM FAIL MSG. LG WOW SYS FAIL CAUTION LOUD THUNK NOISE ON NOSE GEAR RETRACTION MSG WENT AWAY AFTER EXTENSION RTF DFW. EMERGENCY DECLARED. -C/A-PERFORMED OPERATIONAL TEST OF LANDING GEAR EXTENSION AND RETRACTION SYSTEM IAW EMB 175 AMM 32-33-00-710-801-A. OPERATIONAL TEST GOOD.