if its just the hybrid part that won't kick in then yes its probably being effected by the cold weather as low battery temperature will prevent it from functioning correctly
I'd suggest to 1st check the main vehicle battery ( 12v) connections and for tightness and cleanliness
if thats OK then the next step (and is best done by a qualified High voltage battery technician with extensive experience with the high voltage hybrid vehicle) is to have the high voltage battery tested,the high voltage fuse checked,the high voltage cooling system checked to make sure it is o.k. and the high voltage power cable as all of these are components that can cause this issue here.
This is extreme voltage and electrocution can occur if not handled and tested properly so a certified technician should be the only one working on this part of the vehicle with the proper high voltage gear being worn and test equipment.
This may be a fault of any of these components listed above and is keeping the vehicle from starting/running until the fault is repaired and all codes are cleared out/erased.
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