Hi there! My name is***** am a computer professional with over 15 years of experience with both Mac and Windows computers, phones, tablets, and printers. It would be my pleasure to assist you with this.
A C3100 error generally indicates an issue with the scanner carriage.
Let's start troubleshooting with the basics. Please unplug power from the device and leave it unplugged for 10-15 minutes. Plug it back in and let me know if you still have the error message.
If you do, please follow these steps and let me know the results:
Look through the copy glass. There are two main parts or carriages. The first part is the assembly with the lamp and single mirror. The second part is the assembly with two mirrors. Both of these assemblies ride on rails and are connected to each other by a system of cables and pulleys. When unboxed, the KM3035 has 3 yellow screws on the upper left cover that lock the scanner assembly to prevent damage during transit.. Were these screws removed when you set up the printer. My guess is that they were if the printer worked at all, even for a little while ,but I wanted to start with basics just to be sure.
Does the scanner assembly move at all when you power the machine on? Look through the copy glass. The scanner cables should be seen connected to the carriages and going around the pulleys; the cables should not be loose or laying on the deck. The home sensor might not be visible to you if the both carriages are in the way, but it is a small black object with two projections. A flag on the carriage slides between the gap created by the projections (this is the home position). Looking through the glass, the sensor is located at the left rear corner and it should not be hanging or tilted.