LG G4 User Manual page 26

WARNING
Do not insert a memory card into the SIM card slot. If a memory card
happens to be lodged in the SIM card slot, take the device to a LG Service
Centre to remove the memory card.
NOTE
Only the microSIM cards work with the device.
•
3 Insert the battery.
4 To replace the cover onto the device, align the back cover over the battery
compartment
24
and press it down until it clicks into place .
Getting to know your phone