Disassembly imilab Xiaomi Mijia EC2 Security Camera CMSXJ11A for replacing the battery. 

Please use this video as a guide for replacing the battery. There is no sound, please turn on the subtitles.
Battery spec
Typ capacity: 5200mAh
Nominal Voltage: 3.63V
limited charging voltage: 4.2V
2pin connector size: 2.2or2.3mm x 2.0mm, pitch about 0.7-0.9mm
My imilab Xiaomi Mijia EC2 Security Camera CMSXJ11A stopped working, so I disassembled it. After removing and re-installing the battery, it started working again, so I'm not sure why it stopped working in the first place.
The front panel was attached with strong double-sided tape and softened with heat. I realized this after accidentally breaking the front panel.
The circuit board unit is fastened internally with four screws. After disconnecting the battery and speaker connectors, the battery housing is also secured to the casing with four screws.
The battery is likely a standard 18650 lithium-ion type, with a voltage of 3.7V and a capacity of approximately 2500mAh per cell. It appears that two of these cells are used in the camera.
#IMILAB EC2 Not working
#Xiaomi IMILAB EC2 won't turn on
#IMILAB EC2 stopped working