Car wont start after swopping common rail

[speedsix2000]

Hi I brought my W204 651 2010 after it having water contaminated fuel then left, previous owner replaced lift/ low pressure fuel pump ans drained tank, i have since replaced the fuel filter and high pressure pump (second hand) and got it running but 3x injectors also damaged. replaced 4x injectors and coded in (reconditioned) had slight misfire and ran lumpy also getting code for low fuel pressure (4 bar on low pressure and 250+ at rail when cranking) thought maybe a rail sensor issue? Replaced common rail with a second hand one but now refuses to start/ fire up. Swapped rail back still turning over and not firing! please help
I have also tried using Autel to bleed fuel system but goes ok until it asks to start engine. I have cracked the unions going to each injector and have fuel.
thanks

 

[Dodipops]

Start at the beginning again, scan it for codes, check fuel pressure data on diag when cranking, also check rpm sensor data when cranking.

Make sure there isn’t a damaged connector like to the the rail pressure sensor.