citreon xantia hdi 1999 mod car wont start?

hello the only instrument lights working on panel are the battery light and a slight flicker of the heater plug light,there is no reading from fuel gauge there is over 6 gallons of diesel in the tank have checked all the fuses they are all complete it appears as if the immobilser is active all fuses in engine bay are complete there are relays to dont no how to test them doors lock and open with transpponder key when i put on the ignition there are no oil light etc etc could this be a immobileiser fault am baffled