[GuidoK]

That you were able to crank it and the meters got all wonky is to me a sign that its not the battery or the alternator. Unless the altenator gives way to high voltage and fried a cpu. So a voltage check is a thing to do, although the battery acts as a line stabilizer (basically a very big capacitor).
Normally when the voltage drops the car wont crank, but you wont see these strange things imho.
The cranking also doesnt sound like a weak battery.

So I think a module is fried/playing up and using current.
That its using current makes it easier to detect; do a current draw and unplug fuses one at the time.

If you're not into automotive electronics it'll be unlikely that you can fix this problem without the help of a specialist onsite.
The instrument cluster is afaik connected within both the I/K-bus communication as the CAN bus communication (they are seperate networks in the car), but that means that virtually all modules can interfere with information going through the instrument cluster.
(although the indicators/meters that move and flicker are all CAN related)
It can also sit in the wiring (lets hope not...)