How do I wash the Stark properly?

Per the manual

• switch the bike off and remove the phone from the dock
• knock off dirt with cold water from a hose
• no pressure washer — water damages bearings and gets into the wiring
• body — sponge with a neutral cleaner (pH 6–8), wheels and spokes — with a brush
• chain — a rag with degreaser
• rinse with a gentle stream, dry in the sun or wipe dry
• once dry, lube the chain: rear wheel lifted, turn it by hand and spray lube, wipe off the excess

Don't turn the chain with the throttle — only by hand via the wheel.