A method of assembling a handheld electromechanical surgical device comprising assembling a handle assembly of the handheld electromechanical surgical device, the assembling of the handle assembly comprising: providing a power pack including: a core assembly having a plurality of motors (152, 154, 156), with each motor having a rotatable drive shaft (152a, 154a, 156a) extending therefrom, wherein each drive shaft is parallel to one another; a processor connected to and configured to control each motor; and a battery electrically connected to the processor and each motor; and an inner housing encasing at least the plurality of motors, the processor, and the battery, the inner housing including at least one control interface (130, 132a, 132b, 136a, 136b) actuatable to control a functionality of at least one of the plurality of motors; providing a sterile outer shell housing configured to selectively encase the power pack therein; inserting the power pack into a receiving cavity of the sterile outer shell housing; and closing the sterile outer shell housing to encase the power pack, wherein the surgical device is configured to transmit a rotation from each rotatable drive shaft (152a, 154a, 156a) of the plurality of motors (152, 154, 156) through the inner housing and the sterile outer shell, characterized in that: the sterile outer shell housing is configured to encase the entire power pack therein; the sterile outer shell housing includes at least one control button (30, 32a, 32b, 36a, 36b) for operative registration with each control interface (130, 132a, 132b, 136a, 136b) of the power pack; and a sterility of the sterile outer shell housing is maintained during the step of inserting the power pack into the receiving cavity of the sterile outer shell housing. providing a power pack including: a core assembly having a plurality of motors (152, 154, 156), with each motor having a rotatable drive shaft (152a, 154a, 156a) extending therefrom, wherein each drive shaft is parallel to one another; a processor connected to and configured to control each motor; and a battery electrically connected to the processor and each motor; and an inner housing encasing at least the plurality of motors, the processor, and the battery, the inner housing including at least one control interface (130, 132a, 132b, 136a, 136b) actuatable to control a functionality of at least one of the plurality of motors; providing a sterile outer shell housing configured to selectively encase the power pack therein; inserting the power pack into a receiving cavity of the sterile outer shell housing; and closing the sterile outer shell housing to encase the power pack, wherein the surgical device is configured to transmit a rotation from each rotatable drive shaft (152a, 154a, 156a) of the plurality of motors (152, 154, 156) through the inner housing and the sterile outer shell, characterized in that: the sterile outer shell housing is configured to encase the entire power pack therein; the sterile outer shell housing includes at least one control button (30, 32a, 32b, 36a, 36b) for operative registration with each control interface (130, 132a, 132b, 136a, 136b) of the power pack; and a sterility of the sterile outer shell housing is maintained during the step of inserting the power pack into the receiving cavity of the sterile outer shell housing. a core assembly having a plurality of motors (152, 154, 156), with each motor having a rotatable drive shaft (152a, 154a, 156a) extending therefrom, wherein each drive shaft is parallel to one another; a processor connected to and configured to control each motor; and a battery electrically connected to the processor and each motor; and an inner housing encasing at least the plurality of motors, the processor, and the battery, the inner housing including at least one control interface (130, 132a, 132b, 136a, 136b) actuatable to control a functionality of at least one of the plurality of motors; providing a sterile outer shell housing configured to selectively encase the power pack therein; inserting the power pack into a receiving cavity of the sterile outer shell housing; and closing the sterile outer shell housing to encase the power pack, wherein the surgical device is configured to transmit a rotation from each rotatable drive shaft (152a, 154a, 156a) of the plurality of motors (152, 154, 156) through the inner housing and the sterile outer shell, characterized in that: the sterile outer shell housing is configured to encase the entire power pack therein; the sterile outer shell housing includes at least one control button (30, 32a, 32b, 36a, 36b) for operative registration with each control interface (130, 132a, 132b, 136a, 136b) of the power pack; and a sterility of the sterile outer shell housing is maintained during the step of inserting the power pack into the receiving cavity of the sterile outer shell housing. the sterile outer shell housing is configured to encase the entire power pack therein; the sterile outer shell housing includes at least one control button (30, 32a, 32b, 36a, 36b) for operative registration with each control interface (130, 132a, 132b, 136a, 136b) of the power pack; and a sterility of the sterile outer shell housing is maintained during the step of inserting the power pack into the receiving cavity of the sterile outer shell housing.