GV500CNA password recovery over USB

PuTTY over direct USB • Tracking/configuration password • October 28, 2026

Use this procedure to obtain a device-specific recovery command through the GPS Unlock form, restore the tracking password, and verify access.

1. Connect the device and configure PuTTY

1a. Find the COM port in Device Manager

1. Connect the powered, locked GV500CNA directly to Windows with a USB data cable.
2. Open Device Manager and expand Ports (COM & LPT).
3. Find Queclink Modem Device and note its COM port. The example below shows COM4; yours may differ.
4. Close any other program using that COM port before opening PuTTY. Keep the recovery session in PuTTY until the unlock and authentication check are complete. No prior password login or donor device is needed.

1b. Configure the PuTTY session

If you already saved the session from the Teltonika PuTTY guide, load it and change only the COM port to the Queclink port noted above. This reuse was verified on hardware.

For a new session, select Serial on PuTTY’s Session page, enter the correct COM port, and set Speed to 115200.

The reused PuTTY screenshots below show COM8 and a saved session named Teltonika. Those are examples: enter your Queclink COM port (COM4 in the Device Manager screenshot), and optionally save a separate session named GV500CNA.

1c. Set serial and terminal options

Under Connection → Serial, use 115200 baud, 8 data bits, 1 stop bit, Parity: None, Flow control: None.

Under Terminal, set Local echo and Local line editing to Force on. Check Implicit LF in every CR to keep response lines readable.

Return to Session, save the settings if desired, and click Open. Type or paste each command separately and press Enter (Return) to submit it. Local echo shows your input; a device response proves receipt.

1d. Confirm communication and firmware

AT

Require OK, then send:

AT+CSUB

The recovery protocol was verified on firmware:

SubEdition: GV500CNAR10A04V19M64

If there is no response, resolve the connection first. If the firmware differs, stop before purchasing an unlock: this procedure has not been verified on that firmware. Retain the firmware identification for investigation.

2. Check device validation

AT+MCUID=?

Proceed only if the response includes:

MCU ID: Get_ValidHwFlag:1

If it reports Get_ValidHwFlag:0, stop before purchasing an unlock and retain that reply and the firmware identification. This is a separate device-validation problem that the online password-unlock form does not repair; losing a password does not normally require modifying the validation record. An ERROR or no reply is not equivalent to a zero flag.

Do not erase partitions, format the device, update firmware, or clear user settings as part of this procedure.

3. Request a fresh recovery challenge

When you are ready to use the unlock form, send this command once in your connected PuTTY terminal:

AT+QLPWD=10

The reply has this structure:

+RESP:QLPWD,protocol,IMEI,challenge,serial$
OK

This illustrates the field layout; the actual reply contains numbers and a trailing $.

4. Submit the full response to the unlock form

Copy the complete line beginning +RESP:QLPWD, and ending $. Visit the GV500CNA unlock form, select Queclink GV500CNA, and paste that line into Fresh device challenge reply. The form reads the IMEI from your reply; check that it matches your device and that your firmware matches the verified version above.

Confirm that you own the device or have permission to recover it, then complete the $5 USD one-time payment. Once payment is confirmed, your order page displays the complete command. Click Copy unlock command and continue to step 5. Save the private order link from your receipt email or bookmark the order page so you can return without paying again.

5. Enter the supplied recovery command

The command displayed on your paid order page will begin with:

AT+QLPWD=11,

Paste the complete command copied from your order page into PuTTY and press Enter once. Do not add quotation marks or a $ suffix. Use mode 11 for the tracking/configuration password.

The response check consumes the challenge, even when the supplied response does not match. Do not resend the same command after a failed attempt. Request a fresh challenge, then paste the complete new reply into the fresh-challenge form on your paid order page to generate a matching command at no additional charge. The reply must contain the same IMEI.

An OK alone does not prove that the password changed. Continue with the authentication check.

6. Verify the reset password

The expected tracking/configuration password after recovery is gv500cna, all lowercase. In the same PuTTY terminal, send:

AT@PROBE?gv500cna,,FFFF$

This command does include the final $. A full reply beginning +PROBE:, followed by OK, confirms that the device accepts the reset password. That authenticated response was observed after direct PuTTY recovery on the tested firmware.

If no full authenticated reply arrives, stop and retain the responses for investigation. Do not treat a generic OK as confirmation.

7. Reconnect and check persistence

1. Close PuTTY so it releases the COM port.
2. Now open Manage Tool Pro and connect to the unlocked device through its login interface using gv500cna.
3. Power-cycle the device and verify that the same password still works. Retain the result to document persistence.
4. After recovery, use the tool to set your desired configuration password and retain it securely.

The recorded hardware test confirmed authenticated PROBE access. Login through the tool UI and password persistence after a power cycle remain verification steps, not established results for this procedure. Do not apply the Teltonika set-then-remove workaround to this device based on the Teltonika guide.

Troubleshooting

• No response in the terminal: use the connected PuTTY serial session described in step 1. Confirm the COM port and serial settings, close other programs using that port, and press Enter after each command.
• Port busy: close other terminal or configuration programs using that COM port.
• AT works, recovery does not: recheck the firmware identification and AT+MCUID=? result.
• Device rebooted or another challenge was requested: request a fresh challenge and use the complete new reply on your paid order page to generate a matching command at no additional charge.
• Need DMS/QMS access: that is a separate password and procedure. This guide resets only the tracking/configuration password.