Power source retention system

A power source retention system comprising:

• a power source including an outer casing and a locking member mounted on top of the outer casing and configured for rotation about a vertical axis relative to the outer casing;
• and
• a power source compartment configured to removably receive the power source into a power-source-receiving space in a vertical direction, the power source compartment including a retention member located adjacent to the power-source-receiving space;
• wherein when the power source is in the power-source-receiving space, the locking member is rotatable about the vertical axis in a locking direction to a locked position in which the locking member engages the retention member to block the power source from being upwardly removed from the power source compartment, and the locking member is further rotatable in an opposite, unlocking direction about the vertical axis to an unlocked position in which the locking member is unengaged from the retention member to allow the power source to be upwardly removed from the power source compartment.