Straight from Canon's knowledgebase:
Unfortunately, this is an unrecoverable hardware error and repairs are no longer available for this product due to its age. If you wish to move up to a newer product, please contact our Customer Support team at (866) 443-8002 to explore your options. Turn off the machine, and unplug the power cord of the machine from the power supply.
If you have unplugged and power cycled, there isn't much else to do.
Bay Area - CA
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Thanks. It's been a good machine and even though it's fairly old I'm sure it hasn't been used much as printers go. I'm not very electronics savvy but other than occassional print head cleaning I can't imagine much should go wrong with a printer like this as long as it isn't something that moves or mechanical. PLANNED OBSOLESCENCE maybe? Oh well, they're fairly inexpensive so a new one might be nice. After seeing all the problems people have had with various Canon printers, I won't be buying another Canon. Maybe a Brother or HP?
07/31/2023: New firmware updates are available.
05/31/2023: New firmware updates are available.
05/18/2023: New firmware updates are available.
04/20/2023: New firmware version 1.4.1 is available for EOS R3
03/30/2023: New firmware updates are available.
2/07/2023: New product announcements!EOS R8 EOS R50RF-S55-210mm F5-7.1 IS STMRF24-50mm F4.5-6.3 IS STMRF15-30mm F4.5-6.3 IS STM