How To? - "Unbrick" a Tenda AC15 WiFi Router

In this article I describe the steps that I went thru to attempt to unbrick a Tenda AC15 WiFi router.

Issue

My Tenda AC15 WiFi modem decided to brick itself. I was not attempting to use the modem with any other firmware, etc. that would typically brick a router. I was using it with the stock firmware on it. In fact, I had never updated the firmware (despite the fact that the router has known security issues) as it had the latest available from Tenda. I was, however, using it in a mode where it was trying to manage around 50 IoT devices on a single radio and it was struggling - i.e. it started refusing device connection requests, etc. I did not realize the issue (being too many clients) until it was too late as I already had attempted factory resets on  the router but this activity may have caused my issue? My factory reset attempts may have somehow put the router in a state that it is now "non-functional" or "bricked".

For a Tenda AC15 - expected default IP settings

Symptoms

• LEDs are out - including the "SYS" led
• This means no WiFi, no SYS, and no LAN leds.
• The router no longer provides a local LAN address to any device.
• There is no response to the default gateway address of 192.168.0.1
• Attempts to hold the reset button (using a paperclip) does not appear to reset the device to factory defaults (i.e. provide a functioanl device)

Troubleshooting

I researched options but there is not a lot of information available on how to recover a AC15 so I tried a number of things.

The device was not responsive at all - the lights were dim on the front of the modem.

Step 1 - Try another power supply

I tried another power supply. Same results so its not the power supply.

Step 2 - Do a 30-30-30 on the router to reset it to factory defaults

"30-30-30" Router Reset - Also known as the "90 Second" Reset

• When the router is powered on, press the reset button and hold for 30 seconds.
• While holding the reset button pressed, unplug the power of the router and hold the reset button for 30 seconds
• While still holding the reset button down, turn on the power to the unit again and hold for another 30 seconds.

I tried this and the router "SYS" light came on and stayed on. But no still response at 192.168.0.1

Step 3 - Try to "tftp" a firmware to the device

I decided to try to get to the router using a 30-30-30 reset and define an IP address for my laptop with the default gateway being the factory reset default gateway (i.e. 192.168.0.1)

Procedure to TFTP a firmware to a device:

1. Disable the Windows Firewalls
2. Turn off Domain, Public and Private Network firewalls.
3. Download a valid firmware - go to the Tenda website and grab a firmware for the AC15
4. Rename the firmware file "AC.bin"
5. Do a router reset - execute a 30-30-30
6. Connect the computer via LAN cable into WAN port of router.
7. Go to Network properties of the Ethernet connection and update the LAN IP settings (see pic above)

Change the adapter to "Manual"

IP: 192.168.0.10 (provide an address for the laptop)
Mask: 255.255.255.0
Gateway: 192.168.0.1
Primary DNS: 192.168.0.1
Secondary DNS: 192.168.0.2

Note: successfully set IP settings on ethernet adapter

1. Enable the TFTP Client Service on the laptop
   • Control Panel - Programs and Features - Resources and Programs - Turn Windows Features on or off
   • Pick "TFTP Client"
2. Run CMD as administrator and use the command: tftp -i 192.168.0.1 put AC.bin

Note: Failed to transfer the file

Attempted to even ping the default gateway

Note: Failed to ping the gateway

1. Wait for message: “Successful transfer”
2. The router should reboot (or force a restart)
3. Return the Ethernet adapter to Automatic, turn back on the windows firewalls on the laptop

Results - No Success

After spending numerous attempts, including opening the router to make sure I was holding down the reset button and timing using a stop watch on my phone - The best I could do is get the SYS light to stay on permanently and get the WAN led to flash showing that it was alive and managing traffic. However, I could not transfer a file nor could I even ping the router default gateway. I was hoping that the 30-30-30 factory reset would have either reset the firmware or at the very least allowed me to TFTP a file to the device?.

Just in case, I also tried other default gateway addresses - 192.168.1.1, 192.168.2.1, 192.168.3.1, 192.168.0.254.

Currently I am out of options and the router remains completely bricked unless I can think of any other steps I can try.... looks like "RIP AC15"

Additional Info - Opening the AC15

To open the AC15 (I did this to ensure I was holding down the reset button and to better see which leds were working)

• Remove the two small phillips screws on the back
• Using a small flathead screwdriver - you will see a small notch in the bottom left (from back) of the unit. Using the screwdriver you can pop open the case - proceed around the device with the Screwdriver and it will pop off
• No need to remove the stand on the bottom.