Hi Tenpinrap52! Thanks for posting in the Canon Community Forum. I see that the yellow Alarm lamp and green Power lamp (lights) on your PIXMA MG3520 are flashing.
When both of these lamps are blinking, it normally indicates a mechanical (hardware) problem inside of the printer: I know the lights look as if they are constantly blinking, but if you look at them long enough you will notice a slight pause. You can wait for that pause, and then count the number of flashes (both lamps) until you see another pause. Once you know how many times the lamps are blinking (between each pause), you can visit the following section of the manual to find the error code that it represents:
https://ij.manual.canon/ij/webmanual/Manual/W/MG3500%20series/EN/UG/ug_trouble0300.html
When the page opens, you can scroll down to the section that has the information about both lamps blinking (power and alarm).
A paper jam or obstruction can accidentally trigger most of these errors. If you have not done so, I recommend that you turn the printer off and disconnect the power cable. Then, look for a paper jam inside the printer. If you don’t see a paper jam there, you can take the paper out of the tray and look for obstructions that may have slipped into the tray (pen, pencil, paper).
If you don’t find obstructions inside the printer or in the paper tray, you can reconnect the power cable. If the same error starts flashing after you turn the printer on, that means there is a mechanical malfunction inside the printer.
If you would like us to check if there are other options for the error that your printer is displaying, please write back and tell us how many times the lamps are blinking (between each pause). It will also help if you let us know when the printer was purchased and if you installed an ink cartridge immediately before the lamps started blinking.
I hope this information helps. Thanks again.
