Bosch SGS43452GB dishwasher?

Arrrggghhh. Sorry chaps; this has got to be a long one since I’m brand new to the DW problems game. Just been given the Bosch DW above, plumbed it in fine and did a 'Quick' program test run on a couple of small items. Didn't know what to expect really not having had a DW before, but it seemed to do a pretty good job - nice and warm too - almost dry, even though I realise this program doesn't have a drying sequence.
Anyway, finally positioned it (on top of our WM – small house), and got it gleaming to match our WM, loaded it up (about 75%), and now it won't do anything of consequence. Namely: it makes a few clicks, and whirrs and sounds promising, but doesn't seem to progress beyond about 3-4 minutes. It sounds a bit like the drain pump is constantly on but with no water to pump. Quite a faint smooth noise. I tried an obvious way to see if it IS draining by putting about 4 or 5 litres of water in and switching on. Yes the pump now makes a more definite pumping noise and the drain hose pulses very so often until no water left presumably.
I'm an electro-mechanical engineer by trade, and have repaired our 'old' (Hotpoint) WM loads and loads if times over 12 years or so, but not knowing the finer points of what systems DW's have I don't really know where to start a diagnosis. Having said that, and having read quite a few threads on various sites, I'm going to take the RH side panel off after posting this thread to see what sort of parts are accessible. Because of the WM repairs, I understand certain basic principles like filling to certain level on air pressure diaphragm before starting washing sequence etc., and have encountered de-soldered relays and burnt PCB's etc., and so I feel that I am capable of fixing the DW once I know where certain parts are, and what sequence things are done in. Any help re’ location of parts and sequences would be greatly appreciated. It's always very gratifying to NOT have to pay £140 or so for an £8 item and 20mins work, and even that is dragged out sometimes to justify the charges.
BTW way, there were no reported issues at all from the previous owners, and the only reason they got rid of it is because they're having a complete new kitchen fitted and had a new DW thrown in as an incentive. Thanks guys (and girls). Mark in Chesham p.s. Obviously I’m happy to answer any questions in far more detail, and try various test procedures etc.