Disco electrical fault- Help!

Hi all, this fault is attached to another fault I've already listed but still need some help please.
I have a 98 model 300TDi auto Disco 1 and recently I had to remove the Digital Diesel Solenoid (non starter).
After taking the ignition feed from the three DDS cables, I got the vehicle started but, after a few miles of driving, the interior lights came on (and now wont go out), rear wiper wont work and neither does the "key in ignition" bonging noise if the doors open. Also, when I lock on the blipper, the horn beeps twice as if a door is open.
I've read it may be an MFU fault but dont want to buy one if its more to do with the DDS immobiliser system (as they're chuffing expensive!).
Anyone got any experience of these??
Thanks in advance for any help!

Ok, bit of an update.
I've renewed the MFU now with a known good one and the following has happened:
1. Now my interior lights wont come on
2. The "key in ignition" noise has returned
3. I still have no rear wiper
4. I still get the double beep when I lock with the blipper

On a further note, If I get in the vehicle and try and lock it by pushing the lock-fob down or try locking with the key in the lock, the locks bounce back up and wont stay down. Not sure if these faults are related though.

Still looking for any help or ideas out there!

Thanks again!