canon 5d mark ii won't turn on

[woodysg1]

While shooting video, I changed my card and battery. Turned camera back on and nothing. Changed with another battery and card. Still nothing

[Samsen]

Sorry to hear that.

Next thing to do is to remove that coin (Lithium ion) battery and wait for few minutes before placing it back and use a freshly charged battery, a new memory card. Make sure memory card reader door is not damaged and closes fully.

 If still nothing happens, contact Canon' repair center. LINK