canon pixma mg3620 stop button won't do anything, the light just stays on

Diagnosis

The Canon PIXMA MG3620 "Stop" button (marked with a red circle and triangle) is not a general power or reset button; it is a command trigger for specific interrupt and maintenance functions. When the light stays on and the button appears unresponsive, it typically indicates a "Logic Lock" or a "Critical Error State." This happens when the printer's internal firmware is waiting for a specific hardware resolution—such as a cleared paper path or a recognized ink cartridge—before it will accept any one-touch commands. In many cases, the printer is stuck in a communication loop with the computer or smartphone. If a corrupted print spooler file is sent to the MG3620, the printer enters a "Busy" state. Because the Stop button is designed to cancel the current job, if the job is frozen in the printer's RAM rather than the queue, the button will not trigger a cancellation and the status light will remain illuminated to signal that the device is still processing a failed command. You can confirm this by attempting to print a "Nozzle Check" pattern; if the printer ignores this internal command as well, the issue is a firmware freeze rather than a mechanical button failure.

How to Fix It

To resolve a frozen Stop button and clear the internal error state, perform a Hard Power Cycle and a Queue Purge. Follow these exact steps:

1. While the printer is powered on and the Stop light is lit, pull the power cord directly from the back of the MG3620. Do not use the power button.
2. Disconnect the USB cable (if applicable) from the printer to prevent the computer from automatically sending the corrupted job again.
3. Wait exactly 60 seconds to allow the internal capacitors to discharge completely.
4. While the printer is unplugged, press and hold the Power button for 15 seconds to drain any remaining residual energy from the logic board.
5. Plug the power cord back in and turn the printer on.
6. On your computer, navigate to "Devices and Printers," right-click the MG3620, and select "See what's printing."
7. Go to the "Printer" menu and select "Cancel All Documents." This clears the Windows print spooler so the printer doesn't immediately freeze again upon reconnection.
8. Reconnect the USB cable or reconnect to the Wi-Fi network.

If That Didn't Work

• Perform a Manual Ink Reset: If the Stop button is unresponsive because of an "Ink Out" error (Error E05), the printer may ignore commands until the ink level is reset. With the printer on, press and hold the Stop button for exactly 5 to 10 seconds. This forces the printer to ignore the ink level detection and allows the Stop button to regain functionality for other maintenance tasks.
• Check for Carriage Obstructions: Open the scanning unit/cover. Manually slide the ink carriage from the far right to the far left. If there is a tiny scrap of paper or a displaced piece of packaging foam blocking the path, the printer enters a "Carriage Jam" state that disables the Stop button's ability to cancel jobs. Clear any debris and close the cover firmly.
• Reset the Network Interface: If the printer is frozen due to a wireless handshake error, press and hold the Stop button until the Power lamp flashes 15 times, then release. This resets the internal network card, which often unlocks the control panel if the freeze was caused by a network timeout.
• Update the Firmware: Use the Canon Update Tool on a PC to check for firmware revisions. Logic locks on the MG3620 are frequently patched in firmware updates that improve how the printer handles oversized print spools.

Heads Up

• Avoid using "Generic" or "Compatible" ink cartridges that lack a proper chip; an unrecognized chip can trigger a persistent error state that makes the control panel buttons unresponsive.
• Never pull paper out of the printer in the direction opposite to the normal exit path, as this can bend the pickup rollers and trigger a permanent "Paper Jam" error that disables the Stop button.
• If the Stop light is flashing in a specific pattern (e.g., 2 flashes, 5 flashes), this is a diagnostic code. Count the flashes carefully, as this indicates a specific hardware failure (like a waste ink absorber full error) that cannot be fixed with a button press.
• Keep the printer on a surge protector. Voltage spikes can cause the MG3620 logic board to enter a "Safe Mode" where only the power button functions.