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Bricked R8500 unable to get to CFE

iRenaissanceMan
Aspirant

Bricked R8500 unable to get to CFE

Hi,

I've been trying to resurrect my bricked R8500.  I've read most of the forum material on bricked R8500 and followed peter11742's journey.  

https://community.netgear.com/t5/Nighthawk-WiFi-Routers/R8500-bricked/td-p/1183741

 

My problem is that I cannot seem to get the CFE prompt.  I got it 1 time and I was able to load the firmware (DDWRT) successfully.  However, after restarting, it appears I'm back to the same problem. I wish I had loaded the base R8500 file, but I got ahead of myself figuring I could just jump straight to DD-WRT.  Kicking myself now...

 

I am able to connect to the router via the J4 port and get a read-out.  Weirdest thing... I cannot simply keep the USB cable plugged in.  I have to start the router first, then plug in the usb cable and run Kitty/Putty.  I use Kitty as it seems faster to load.  I've tried CTRL+C throughout the entire load and get nothing.  The router just keeps going on loading until it craps out.  Here's the printout of the connection. I'm hoping you may be able to help me get CFE running on the router.  Thanks!

Model: R8500|Nighthawk X8 Tri-Band AC5300 WiFi Router
Message 1 of 14

Accepted Solutions
labatt
Mentor

Re: Bricked R8500 unable to get to CFE

Yes you need to have the USB cable plugged in and terminal active when you start the router up as the CFE comes right after the power up. If you are plugging in after you start the router then you will miss the CFE unless very lucky. I suspect, as I said earlier, you have a defective USB serial cable. Have had similar issues with bad ones. They are CHEAP and do not hold up well and had one that was defective out of the box. 

 

Best I can do for you at this point is to wish you good luck. 

View solution in original post

Message 8 of 14

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plemans
Guru

Re: Bricked R8500 unable to get to CFE

You need to be on the dd-wrt forum, not the official netgear forum. They'll be the experts in their firmware and whats running wrong. 

Message 2 of 14
labatt
Mentor

Re: Bricked R8500 unable to get to CFE

Time I had trouble with things working correctly with the USB serial cable it turned out to be the cable bad. Even though it seemed to almost work. I assume you are only connecting the two data connections and the ground? Do not connect the +3 volt or what ever it is called connection. You have to watch and react fast to get into the CFE. Have done this process many times over the years. 

Message 3 of 14
labatt
Mentor

Re: Bricked R8500 unable to get to CFE

Above should say not working correctly. Netgear, in their infinite wisdom removed the edit function. 

Message 4 of 14
iRenaissanceMan
Aspirant

Re: Bricked R8500 unable to get to CFE

Thanks for your reply. Yes, only 3 wires connected. Rx, tx, and ground. It's J4 pins 1, 2, 3. I am not using the +3v red wire.

I did get into CFE one time... That's how I was able to load the current file. Unfortunately, I can't seem to get back into CFE. I am pressing Ctrl + C from the very beginning, but no luck.

Any advice would be fantastic. Thanks
Message 5 of 14
labatt
Mentor

Re: Bricked R8500 unable to get to CFE

Cannot really offer any other thoughts. I assume you are following something like this. Works for any Netgear router not just listed. 

https://www.myopenrouter.com/article/how-debrick-or-recover-netgear-r7000-r6300v2-or-r6250-wi-fi-rou...

 

I have never had issue getting into CFE.

Message 6 of 14
iRenaissanceMan
Aspirant

Re: Bricked R8500 unable to get to CFE

Thanks. Yup, that's exactly the steps I've implemented/attempted.

One issue that troubles me... I am not able to keep the USB cable plugged in at initial power on of the router. I have to start the router first and the. Plug in the USB cable to my laptop. Could this be an issue resulting in my failed CFE attempt? I would imagine the router should behave the same regardless of USB cable plugged into Laptop or not. However, the router behaves differently when the USB cable is plugged in and then router started. I get absolutely nothing on Putty if I have the USB plugged prior to starting the router.

It seems like most people have the USB cable plugged in and putty running BEFORE powering the router.

Any thoughts on that?
Message 7 of 14
labatt
Mentor

Re: Bricked R8500 unable to get to CFE

Yes you need to have the USB cable plugged in and terminal active when you start the router up as the CFE comes right after the power up. If you are plugging in after you start the router then you will miss the CFE unless very lucky. I suspect, as I said earlier, you have a defective USB serial cable. Have had similar issues with bad ones. They are CHEAP and do not hold up well and had one that was defective out of the box. 

 

Best I can do for you at this point is to wish you good luck. 

Message 8 of 14
iRenaissanceMan
Aspirant

Re: Bricked R8500 unable to get to CFE

Thanks!  Just closing the loop on the topic.  I took your advice and purchased a new cable from Amazon.  Viola!  CFE up immediately.  Definitely a cable issue.  I opened up the original cable and found a solder bridge across 2 pins on the IC.  Ughhh...  What a waste of time trying with that other cable.  Didn't think to open up the cable to check!

 

 

Message 9 of 14
antinode
Guru

Re: Bricked R8500 unable to get to CFE

> [...] Definitely a cable issue. [...]

 

   "cable" is a rather imprecise description of any gizmo with an IC
hidden inside.

 

> [...] Didn't think to open up the cable to check!

 

   In general, you should be able to do a simple loopback test with any
serial interface: Tie RxD to TxD, and see if you can talk to yourself.
(Hardware flow control can complicate such a test, but this stuff is too
simple for that.)

 

   Wrong speed (or bits, or parity, ...) is the other common problem
(which a loopback test typically won't reveal).

Message 10 of 14
it_geek
Guide

Re: Bricked R8500 unable to get to CFE

I am most keen to know which cable you purchased off Amazon as I will need a replacement serial to USB cable to attempt to unbrick my R8000 routers as well.

 

Please drop the Amazon URL in your reply... Thanks!

 

Message 11 of 14
labatt
Mentor

Re: Bricked R8500 unable to get to CFE

If your present cable worked then no need for another as should work on any router serial connection.  

 

As you asked this is the cable I have. Little more expensive then some, but works. 

https://www.amazon.com/ADAFRUIT-Industries-954-Serial-Raspberry/dp/B00DJUHGHI/ref=cm_cr_arp_d_produc...

Message 12 of 14
it_geek
Guide

Re: Bricked R8500 unable to get to CFE

My present cable snapped due to an accident and I didn't get it myself, a friend passed it to me.

 

I have gotten the said cable and will use it in the diagnosis of my Netgear router.

Message 13 of 14
iRenaissanceMan
Aspirant

Re: Bricked R8500 unable to get to CFE

I bought this one from Amazon. $7

JBtek Windows 8 Supported Debug Cable for Raspberry Pi USB Programming USB to TTL Serial Cable https://www.amazon.com/dp/B00QT7LQ88/ref=cm_sw_r_cp_apa_i_zNTnEb76EG82T
Message 14 of 14
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