1997 BMW 540i No start

Hi there, I thought I would replace the rubbers in the key pad on my 1997 540 I BMW today before reading any blogs about this, My mistake. Since doing this I have no start.I have since read most blogs I can find and tried them all, only to have this result.
I unlock drivers door with key. Close door and insert key to 1st position.I've tried pushing the num1 pad first and hold down the 2 nod pad for 3 seconds, then for 10 seconds, alternately using the first then second pad.
I've held it up to the mirror whilst doing these processes, I've disconnected vehicle battery and key fob again and gain to try and set my key to the vehicle.
The best result I've had and since lost was to have control over the windows and sunroof, along with control of Central locking from key pad, with basically all electrical components working like radio, lights, indicators. Etc.
But not once have I been able to start the engine again?
I'm getting a little frustrated as it's a few days until Xmas and I've not been shopping yet or even close to getting there.
I don't want to have to tow down to the local wharf and push it in the tide as I've only just got it. And gone thru the complete stereo and amp issues to have good music and video ability.
I've hooked up a snap on analyser to get a code of #148 immobiliser fault.
This has to be the issue but can't sort.
Any ideas be gratefully accepted to getting going. Thanx n advance.