can anyone please help ? i foolishly removed the instrument cluster to try and find an annoying rattle but now i put it back the immobiliser light flashes and cuts the engine i have a very important journey to make so any help would be greatly appreciated , i tried the re solder top too pins as shown in a thread on here but no luck ? i also tried the letting imobiliser cut it then leaving key in as someone also mentioned but again no joy ?

ps . key still operates the central locking 

after trying disconnecting and reconnecting the battery ,removing and reinstalling cluster ,changing battery in key and previously mentioned ideas , disconnecting and reconnecting ecu seems to have worked ,touch wood! just have an air bag warning light on that wasnt there before ? though just relieved its drivable again