Many verified cases of "Download Standby" resolved simply by:
Canon part number for compatible DIMM: WG8-5655-000 (64MB) or WG8-5961-000 (128MB). Aftermarket equivalents: Crucial CT16M64S4D7E, Samsung M470L2923BT0.
The iR2016’s power supply unit (PSU) must deliver stable 3.3V and 5V DC to the controller. Ripple or undervoltage can cause boot failures. The printer detects this instability and parks itself in Download Standby instead of attempting a full boot, which could result in data corruption.
You will need:
Never turn off the copier or disconnect cables while the "DOWNLOAD STANDBY" or "WRITING" message is on screen. Even if it takes 20 minutes, let it finish.
The Canon iR2016 is an older device that often connects via a IEEE-1284 compliant parallel cable. Modern, cheap, or non-compliant cables do not meet the voltage or signal timing requirements. A poor cable can send garbage data during a handshake, causing the "Error Verified" flag to trigger.
After fixing the error, take these steps to ensure it never returns.
“Verified Download Standby Error Auto-Resolution”