Won’t start after changing glow plugs

Hi all can anybody help. I just purchased a td4 2004. I’ve tried to change the glow plugs . two plugs have snapped in the head but there still in the head so I put the 2 back on them .So I only changed the other 2 with new glow plugs .I then replaced and cleaned the intake manifold and sensor .cleaned the egr replaced the vacuum pipe as this was split .the rear fuel pump is firing up .And the battery is strong then put some easy start down the air intake still It won’t fire. Totally fed up any nights in shining armour out there how can help

You need to get some live data from the ECU with a suitable code reader, or you'll just be guessing as to the problem.