Canon Service Tool V-4713 !!install!! Download Page

: Using an incompatible version of the service tool or entering "Service Mode" incorrectly can "brick" the printer’s logic board, making it permanently unbootable.

While holding Power, release Stop/Reset and then press it (or 6 for some models).

– though the V-4713 tool does not natively support backup, some modified versions do. Proceed at your own risk.