EOS 5D MarkII
Firmware Update Procedures
Precaution
A power failure during the firmware writing operation may disable the camera.
Use a fully charged Battery Pack or dedicated AC Adapter Kit (Optional) ACK-E6 for the firmware update.
Do not shut off the power during the firmware writing operation.
Do not open the CF card slot cover during the firmware writing operation.
Do not press any camera buttons
during the firmware writing operation.