Range rover 2.5 dt 1995 p38 nightmare

Hi im new to this site and im having a nightmare with my p38 . Bought range rover last week battery drained , changed battery now car is asking for key code , got it from lr tried it and its having none of it now showing key code lockout engine disabled . Can i bypass the immobilzer to get it started or any alternative way

driving me insane:

Finally unlocked immobiliser :d problem now saying bonnet open (when its shut) and air bag faulty (fuses fine) . Also fuel seems to be draining back on itself so wont start

Time to get yourself into the Range Rover section and post in there....all these issues have been seen before!