Unbrick ASUS RT-N66U

I recently acquired a bricked ASUS RT-N66U. It is most definitely bricked and refuses to take any firmware loads or allow any communication whatsoever.

After chasing down the usual couple hundred or so rabbit hole dead ends on the Internet (which includes ASUS support) I found a solution and it worked for me. It may work for you.

What is needed is the ASUS Firmware Restoration Utility, which, according to some sources, ostensibly, works on all ASUS routers. I cannot confirm that claim having used it only on the RT-N66U.

I finally found the utility download via this thread --

Here is a direct link to the pertinent download --

For some reason ASUS has decided not to include this utility on the RT-N66U support page, but it turns out that if you go to the RT-AC68U support page the utility can be downloaded from there -- https://www.asus.com/us/Networking/RTAC68U/HelpDesk_Download/

Preliminary: Download and install the ASUS Firmware Restoration Utility. Download the ASUS RT-N66U firmware from their support page -- https://www.asus.com/us/Networking/RTN66U/HelpDesk_Download/ Connect the router to your PC via a UTP Ethernet cable. (Disconnect any other wireless or wired connections you may have to your PC.)

Step 1) Hold down the reset button and power up and keep holding it down for 30 seconds (some resources say 10 seconds but I held it down for 30). This step, ostensibly, puts the router in "rescue mode" according to various sources and the power lamp will blink slowly. The router given to me was, evidently, already in this mode, but I did this step anyway.

Step 2) Launch the ASUS Firmware Restoration Utility and install the firmware.

It will take several minutes to complete the firmware load.

JTAG and TTL serial UART are not the same

You don't need JTAG if the the bootloader is still working

Please expound. Which do I need? How do I deploy either? (Rest of message deleted as it was inappropriate.)

UART, or simple "serial", not JTAG.

More information about serial port:

You should always consider that nobody is really knowing the 100% correct answer, especially only 3h after your posting. Please allow mother earth to do one full rotation (24h), so you message can reach users all over the world.

General info on vendor specific unbricking:

In your case: https://www.asus.com/support/faq/1000814/

Please report back if you succeeded.

1 Like

Update: I found the utility on the ASUS website. My original topic post to this forum has been edited to reflect that.

Thank you. I found this, but in their infinite wisdom, the critical utility needed can be found nowhere on the ASUS website. I am editing my original post with a solution I have discovered.

I'd also say, I was kinda shocked. I would have surmised that someone who purchased a bricked router knew how to use those tools already. Some people get upset that you're babying them or treating them like a fool. You'd be surprised.

In addition, you didn't ask for an example.

I simply connect the serial cable. Depending on how your device is bricked depends on the procedure.

You were already told about the bootloader. If you see the bootloader when connected so serial, you should be able to proceed from there.

I don't know the TFTP procedure for your specific model.

It's just standard TFTP put.

You could make another post.

Fair enough. I was simply responding to mbo2o hoping to get a better understanding and some more detail. I take it I annoyed some folks. That was not my intent.

Please do. Because it was my intention to contribute:

  • Standard TFTP
  • Procedure is unique to the device
  • Didn't wish to insult
  • Post your success for the rest of the community to benefit

Yet you insult. Guess you are seeking a fully-written manual.

Let's just wait for the eatrh to rotate, then.

BTW... I also added.

So perhaps you should provide more details in the meantime, too.

@dkwalton The devicpage https://openwrt.org/toh/asus/rt-n66u is lacking information regarding unbricking / installation. If you succeed with unbricking, the devicepage would be the ideal place to add the unbricking information.

Good luck with the unbricking! :slight_smile:

1 Like

I don/t even know what a bootloader is.

Re: "Yet you insult. Guess you are seeking a fully-written manual.

Let's just wait for the eatrh to rotate, then.

BTW... I also added.

Depending on how your device is bricked depends on the procedure.

So perhaps you should provide more details in the meantime, too.".

Oh for crying out loud.

Back off. What is your.problem? I have insulted no one. Evidently you missed the details which are given in the second sentence of the topic post. I am doing the best I can, which evidently does not measure up to your standards.

Please feel free to never answer any posts I may make here in future. I find you presumptive, personally insulting and unhelpful. Clever by far though with your silly "take downs." You must live for such.

This sort of nonsense is NOT why I joined this forum. To bicker with someone I don't even know when all I seek is to share and garner knowledge. If you want to spend your time chastising folks, join a Yahoo chat room.

If this is how this forum is going to go, then I have only one more question: How do I delete my account?

Sure, let me remote your machine; and I'll fix all up it for you.

Then you definitely won't be needing JTAG.

But if you want gain knowledge have a look here

In any case unless you at least have a working bootloader the UART (serial connection) will not work.


In my original post I wasn't offering any suggestions on how to un-brick any device. I was just politely pointing out your error/confusion. That UART (serial) and JTAG are unrelated so that you may educate yourself in that area as a minimum and hopefully anyone else reading this PUBLIC forum doesn't git mislead by your post.


Many people refer to serial as TTL this is possibly confusing. It should be refereed to as UART or just Serial comms.
TTL refers to the voltage so a 5V UART is a TTL UART
but in the case of 3.3V UART that is technically CMOS.

So what is JTAG for

When a manufacture puts together a device it is generally blank. Since there is no bootlaoder they need/use JTAG to program the ROM/Flash with the bootloader and any other software or data they desire. They can even use it to test the hardware by programming temporary tools for the purpose of testing and diagnosing hardware. In summary it is an engineering tool used in manufacturing electronics.
So JTAG can be helpful to you if you have the skill and technical knowledge of your hardware to re-manufacture it if the bootloader has been bricked not just or OEM or OpenWrt firmware.

1 Like




Sure, let me remote your machine; and I'll fix all up it for you.

I am sure you would. Run along now. I am done with you, dear heart. If I ever desire to have an extended conversation with a sociopathic troll again I'll be sure to look you up. Please don't take that as an insult. It is, "Just the facts Ma'am."

1 Like

Thank you mbo2o and Das U-Boot. I guess I do know what a boot loader is since I have long worked with such building Windows machines (and DEC machines before that). I just don't get it with consumer/business routers which to me are arcane and confusing. I suppose if I went ahead and built an OpenBSD machine with a couple/three wired and wireless NICS this whole routing business would make more a lot sense to me. (In fact, I should have done that years ago. Maybe this should be my next step.)

Related Subject You Might Address? --.

There is this open source thing called Tftpd. It comes in 32 bit and 64 bit flavors. Evidently it can be used as a sort of universal firmware loader for various and sundry consumer/business routers. Do you know anything about this utility?