Failure to Check the Drain of Relief Valve in Fuel System

Main Engine start fails because of No fuel oil pressure in the rail (RTA flex Engine). At Newark main Engine Piston pull was planned, fuel pressure from the rail and accumulator were made zero, by keeping the drain of the relief valve open, with the help of a screw driver. The same was not removed after the completion of the job and it was totally forgotten. During departure engine failed to start because the fuel drained through the drain of the relief valve.