What weight oil is in it?
Was it plugged in?
Do you have a battery blanket?
If the motor started to turn over when you jumped it without the key in - sounds like the aftermarket control is still stuck in start mode - if it is and was trying to turn the motor over orginally - it pumped current through the battery like mad. At -20 a discharged battery can freeze in a couple of hours making it toast. Try to get the remote start to disengage and slap a charger on your battery while you are waiting because if your battery was drained by the remote start it will freeze shortly unless you get a charge back into it. Remember that a fully charged battery has less than 50% of it's cranking amps at -20 a battery blanket will keep it warm and give the battery maximum cranking power. Here on the prairies - 10w30 is too thick for an engine not plugged in to turn over very fast at -20 - 5w-30 or similar makes turning the motor over easier. Keep us posted.
Morris - in freezing Manitoba