E46 M3 dash / instrument cluster not working. Any ideas?

[Wolfer]

Hi all, hoping this isn't something bad, although the way my luck is going it will be!

My 01 / 02 E46 M3 has been sat for 6 weeks. Went to start it, dead. Hooked up my old Peugeot to it, left it running for ages, but still wouldn't start.
Took off battery, had it tested and it was faulty, so have a brand new one on.

Now I've just put new battery on, but, nothing comes up on dash, including what gear you are in (SMG) only the handbrake light. Rev counter etc not working either. But it does start.

What have I done?

The Peugeot is gone now, and only have this. But obviously can't drive it. as cant even see what gear I am in or how to change it.

I have removed the BM54 unit as have been told that could have caused it, also checked and reseated fuses 10, 34 and 43.

Thanks