Canon PowerShot SX400 IS Black Manual (en)

If you think there is a problem with the camera, first check the 
following. If the items below do not solve your problem, contact a 
Canon Customer Support Help Desk.
Nothing happens when the power button is pressed.
Confirm that the battery pack is inserted facing the correct way (= 28).
Confirm that the memory card/battery cover is fully closed (= 28).
Dirty battery terminals reduce battery performance. Try cleaning the 
terminals with a cotton swab and reinserting the battery pack a few times.
The battery pack runs out of power quickly.
Battery performance decreases at low temperatures. Try warming the 
battery pack a little by putting it in your pocket, for example, ensuring 
that the terminals do not touch any metal objects.
Dirty battery terminals reduce battery performance. Try cleaning the 
terminals with a cotton swab and reinserting the battery pack a few times.
If these measures do not help and the battery pack still runs out of power 
soon after charging, it has reached the end of its life. Purchase a new 
battery pack.
The lens is not retracted.
Do not open the memory card/battery cover while the camera is on. 
Close the cover, turn the camera on, and then turn it off again (
The battery pack is swollen.
Battery swelling is normal and does not pose any safety concerns. 
However, if battery swelling prevents the battery pack from fitting in the 
camera, contact a Canon Customer Support Help Desk.