1. A method for starting an internal combustion engine of a multi-mode powertrain system including a high-voltage electric machine electrically connected to a high-voltage electric power system, the method comprising: in response to an operator initiating a jumpstart: electrically connecting the high-voltage electric power system to a remote electric power source; energizing contactors between the high-voltage electric power system and the remote electric power source; minimizing electric power flow through an auxiliary power module electrically connected to the high-voltage electric power system, wherein the auxiliary power module supplies electric power to an accessory device; modifying engine starting parameters; and starting the internal combustion engine by controlling, via a controller, the high-voltage electric machine to spin the internal combustion engine, and controlling operation of the internal combustion engine based upon the modified engine starting parameters.