Canon ImageRunner iR8500 Series Service Manual page 1110

Chapter 18
4) Click [OK].
5) Turn OFF and back ON the main power.
Never turn OFF the power of the machine while the machine executes writing. If the power is turned OFF at this time, the writing is interrupted, and the
machine fails to start up as a result.
When the machine does not start up, format BOOTDEV using the HD format, and then download System, Language, and RUI.
6) Turn OFF and back ON the main power according to the screen on the control panel.
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