Slackening the nut and watching for a free flow of fuel....no bubbles or farts whilst it is cranking ensures that the fuel system is air lock free.
If you have fuel feed and the injector pump is doing it's job, you should be able to start the beast.
Resynching only allows the glow plug relay and starter to work as they are controlled by the Becm/engine ecu handshake which comes down to the code stored in the Becm matching the engine ecu code.
I repeat, you need the Glow plug & Injector light on before you can start the engine...if you have only one of these, chances are it needs a resynch. if you have both then the chances are you are not getting fuel through.