Car not starting!!!

I could never survive your cold winters! Fro your engine to start it must crank over fast enough which with a new battery if your starter motor and power and ground cables are OK your Sienna should crank over fast enough. In your extreme winter conditions the incorrect viscosity of oil may also effect engine cranking speed, your Toyota calls for 5/30Woil. Next your car needs fuel in the best of conditions your car needs "extra" fuel to start from cold (even during a start in the middle of summer) as fuel atomizes best in an engine that is at operating temperature. Your Sienna is fuel injected. Their is a sensor in the engine that reports to the Fuel Injection computer how cold the engines coolant is. If the Coolant temperature switch or ambient air temperature switch are not giving an accurate reading to the computer the fuel injection computer may think its a fine summers day and not be injecting enough fuel into the engine. More likely if the ignition system is in any way compromised the spark gong across the spark plug will not be sufficient to start the engine. Lastly a worn out or tired engine will not develop enough compression to start. Once the engine has started does the engine run fine? When cranking the engine from a cold start when it does "fire up" does it run OK while it is starting up. I have seen the Idle air control motor stick open or partially open which causes the engine to stall once it has started. Hope this helps but it is impossible to be more precise without being able to exhibit the starting problem first hand.

your symptom indicates a starter went bad. Our shop in St Paul, MN deals with starter issues a lot when its -15 out. typically a starter in MN will last about 100,000 due to our extreme weather conditions