Display won't turn off - draining battery

[Ubernoober]

The lcd panel on my twin-dial dash Mk2 came on at some point after I had parked up and so drained my battery. As soon as I connected the jump leads it came on and now won't turn off.

Any ideas??

[Ubernoober]

Correction, ignition wont turn off - still won't start though - just chatters.

Probably the switch itself??

[Ubernoober]

New battery fitted (joy unbounded doing that!) - the old one was truly shot, wouldn't hold a charge.

However, still got the fault - most obvious symptom is that the power feed to fuse 18 comes back on after car is switched off and key removed. This can be shown by either with the lcd dash/leds not switching off at all or having it come back on after anything up to an hour later.

Hopefully pulling this fuse, which powers the lcd, leds and some motors under the dash judging by the whirring, will stop the battery drain. Car still starts ok and doors open ok with it removed.

Not having a wiring diagram, I have no idea where the feed to this fuse originates.

Any one out there with a wiring diagram??? Or maybe have an idea as to what the root cause could be??