When should I consider the print head damaged if Canon error E05 appears?

If you've tried all the basic troubleshooting steps, including reseating the print head and cleaning contacts, and the error E05 persists, it's possible the print head itself is damaged or has failed. Look for any visible signs of damage, such as bent pins or cracked plastic. If the printer is still under warranty, contact Canon support for a repair or replacement. If not, you may need to purchase a new print head.