Why does a new JLWM1203 show lights yet do nothing but lock door?

Brand new John Lewis Washing Machine
JLWM1203 [Electrolux] PNC {Prod No} 9145 22514/00
has been connected and empty cotton wash selected as advised in On-line Video & Handbook. Press Start/Pause
and the door clunks locked; brief second of apparent
"activity" and then nothing -- indicators on, door lock on, but Select/Pause light is now flashing! Nothing else!

Clearly the mains are connected, the water is connected (a
sink tap, and a dishwasher on a forked junction draws water OK) and the outlet is connected (another junction into the sink outlet) as required.

Where is the fault likely to be?