As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LAX FLIGHT NR 2444: NR 3 HYD CAUTION LIGHT ILLUMINATED DURING PUSH BACK. AIRCRAFT RETURNED TO BLOCK. MAINTENANCE OPERATED NR 3 HYD ISO VALVE AND CYCLED ELEVATOR SEVERAL TIMES. C/W PRESSURIZATION CHECK OF NR 3 HYD SYSTEM IAW Q400 AMM TASK 29-00-00-863-803. OPS CHECK GOOD. CAUTION LIGHT REMAINED EXTINGUISHED. NO DEFECTS NOTED. NO PARTS REPLACED. AIRCRAFT RETURNED TO SERVICE.