Nikon D5500 Reference Manual page 52

3
Insert the battery and memory card.
Before inserting or removing the battery or memory cards,
confirm that power switch is in the OFF position. Insert the
battery in the orientation shown, using the battery to keep
the orange battery latch pressed to one side. The latch locks
the battery in place when the battery is fully inserted.
Battery latch
Slide the memory card in until it clicks into place.
28 Introduction