Vectra C starting issue / battery running flat

[ColdSyphon]

Hi guys,

My Mrs has a rather ropey Vectra C which has developed a few quirks with age. The car had a new battery & alternator about 18 months ago, however, recently the battery keeps running flat. We think we've traced this to an issue with the stereo/nav which keeps turning itself on randomly.

To fix this, we removed the stereo which seems to have stopped the battery going flat, however the car now won't start. Turning the key in the ignition produces a "tick-tick-tick" type sound, but the car doesn't even attempt to turn over. Any ideas as to what the issue may be?

Cheers

[ColdSyphon]

Turns out the new battery she'd had in 18 months prior was a duff.

Does anyone else have the "feature" where the dash lights up like a Christmas tree and then everything (clocks etc) just die. Doesn't seem to be any pattern or commonality as to what the cause is either.