I have used my Canon products religiously for many years....both Inkjet and Laser. Twice now, I get the incessant "Alarm" light that comes on and will NOT go off. No matter how much you try to "Factory Reset" the unit, it will not turn off the Alarm Light. Trust me....even talking with my buddy who is a Canon Sales Rep....even HE could not figure it out.
However, I may have saved MANY of you from throwing it out the window and spending hundreds on a new printer. When you open the "scan" lid, on the left side, you will see a "feeder bar" bar in white. To the left of that feeder bar, are two white, plastic tabs. Those can sometimes get caught up inside from various reasons....age, gunk, **bleep**, dog fur or anything else you can think of. If any one of those tabs are retracted in in the slightest, it will trigger an alarm. Simply, pull the tabs straight out. They will need to be able to touch the feeder bar and then you know they are out all the way. DO NOT tug very hard....they will pull out easily...no need for force. Once you pull those out, close the scan lid and follow the prompts on the screen. I believe it simply has (OK) somewhere on the screen. Hit that OK button and let it reset itself. The alarm light will then go away. I hope this helps you with your printer.
Side Note: This is NOT in relation to Error 5100/5200.....this is a total separate problem. Once I get a free day, I will take some air cleaner and some electrical keyboard cleaner and clean the tabs. Mine lasted 2 yrs before it had an issue again.
