RT-N66U Power LED fast blinking

[Tibo]

Hi everyone. My router (RT-N66U) dead after reboot.
Power led fast blinking all the time , restore mode working - I tryed clear nvram from web CFI , also tryed all official and alternative firmware - flashing ok, then reboots and rapid power led fast blinking again.

In console I can see:

Decompressing...done
tmp_ret= 0


CFE version 5.100.127 based on BBP 1.0.37 for BCM947XX (32bit,SP,LE)
Build Date: 五 12月  9 10:10:49 CST 2011 (boyau@localhost.localdomain)
Copyright (C) 2000-2008 Broadcom Corporation.

Init Arena
Init Devs.
Boot partition size = 262144(0x40000)
et0: Broadcom BCM47XX 10/100/1000 Mbps Ethernet Controller 5.100.127
CPU type 0x19749: 600MHz
Tot mem: 131072 KBytes

CFE mem:    0x80700000 - 0x8079D320 (643872)
Data:       0x807330F0 - 0x807363B0 (12992)
BSS:        0x807363B0 - 0x80737320 (3952)
Heap:       0x80737320 - 0x8079B320 (409600)
Stack:      0x8079B320 - 0x8079D320 (8192)
Text:       0x80700000 - 0x807330E8 (209128)

Device eth0:  hwaddr 10-xxxx, ipaddr 192.168.1.1, mask 255.255.255.0
        gateway not set, nameserver not set
Null Rescue Flag.
Wait until reset button released...

In CFE mode:

Decompressing...done
tmp_ret= 0


CFE version 5.100.127 based on BBP 1.0.37 for BCM947XX (32bit,SP,LE)
Build Date: 五 12月  9 10:10:49 CST 2011 (boyau@localhost.localdomain)
Copyright (C) 2000-2008 Broadcom Corporation.

Init Arena
Init Devs.
Boot partition size = 262144(0x40000)
et0: Broadcom BCM47XX 10/100/1000 Mbps Ethernet Controller 5.100.127
CPU type 0x19749: 600MHz
Tot mem: 131072 KBytes

CFE mem:    0x80700000 - 0x8079D320 (643872)
Data:       0x807330F0 - 0x807363B0 (12992)
BSS:        0x807363B0 - 0x80737320 (3952)
Heap:       0x80737320 - 0x8079B320 (409600)
Stack:      0x8079B320 - 0x8079D320 (8192)
Text:       0x80700000 - 0x807330E8 (209128)

Device eth0:  hwaddr 10-xxxx, ipaddr 192.168.1.1, mask 255.255.255.0
        gateway not set, nameserver not set
Null Rescue Flag.
Hello!! Enter Rescue Mode: (by Force)

Reading :: TFTP Server.
Failed.: Timeout occured
Reading :: TFTP Server.
Failed.: Timeout occured
Reading :: TFTP Server.
Failed.: Timeout occured
Reading :: TFTP Server.
Failed.: Timeout occured

I can also enter to CFE by ctrl-c:

Reading :: TFTP Server.
Failed.: Interrupted
CFE>
CFE>

CFE>

CFE> help
help
Available commands:

et                  Broadcom Ethernet utility.
show clocks         Show current values of the clocks.
nvram               NVRAM utility.
reboot              Reboot.
flash               Update a flash memory device
batch               Load a batch file into memory and execute it
go                  Verify and boot OS image.
boot                Load an executable file into memory and execute it
load                Load an executable file into memory without executing it
save                Save a region of memory to a remote file via TFTP
ping                Ping a remote IP host.
arp                 Display or modify the ARP Table
ifconfig            Configure the Ethernet interface
help                Obtain help for CFE commands

For more information about a command, enter 'help command-name'
*** command status = 0
CFE>

Can anyone help?
Replacing the reset button will help?

 

[RMerlin]

Your reset button might indeed be stuck. Try turning off your router, and pressing on it a couple of times to see if it can get "unstuck", then boot again.

I've seen a few people over the years who had a similar problem with their WPS button, but it's still quite uncommon.

 

[Tibo]

Your reset button might indeed be stuck. Try turning off your router, and pressing on it a couple of times to see if it can get "unstuck", then boot again.

I've seen a few people over the years who had a similar problem with their WPS button, but it's still quite uncommon.

Router works irregularly, I mean that router works properly once for several attempts of reboot. That's why I am thinking about replacing reset button.

 

[Tibo]

After desolder the button, router turned on properly three times in a row. After that, it works again irregulary with the same, error message "Wait until reset button released...", though there is no longer reset button. Do you have any other ideas?

 

[RMerlin]

No other suggestion, sorry. Could be something on the board triggering a "ghost" button press I suppose. I don't know enough on the bootloader's inner working to be able to tell for sure.

 

[RouterUser]

My RT-N66U stuck in rescue mode with slowly blinking power LED. No sofware manipulation helped. I suspected that it was a hardware problem. Indeed, it was solved in the following way.
I disassembled the router (unscrewed 3 antennas, removed 4 rubber legs, unscrewed 4 screws under them, opened plastic hood, pulled out PCB, unscrewed 6 small screws and removed the flat shield).
I measured resistance between the terminals of "Reset" button. It was zero Ohms in ON position and about 13 Ohms in OFF position. 13 Ohms seemed to be very low. One terminal of the button was soldered to large grounded area, the second terminal was soldered to the small pad that looked like island inside the mentioned large grounded area. It was surrounded by narrow path of insulative solder mask. I found under 40x magnification that there were tiny dotted lines of migrated solder across the solder mask. I cleaned them using cotton wool and alcohol. After that resistance between the button terminals rose up to 4.7 kOhms. I assembled the router and found that the problem disappeared.

 

[dlandiss]

I measured resistance between the terminals of "Reset" button. It was zero Ohms in ON position and about 13 Ohms in OFF position. 13 Ohms seemed to be very low. One terminal of the button was soldered to large grounded area, the second terminal was soldered to the small pad that looked like island inside the mentioned large grounded area. It was surrounded by narrow path of insulative solder mask. I found under 40x magnification that there were tiny dotted lines of migrated solder across the solder mask. I cleaned them using cotton wool and alcohol. After that resistance between the button terminals rose up to 4.7 kOhms. I assembled the router and found that the problem disappeared.

The best example of systematic troubleshooting I have seen for a long time. Congratulations!

 

[jim769]

My RT-N66U stuck in rescue mode with slowly blinking power LED. No sofware manipulation helped. I suspected that it was a hardware problem. Indeed, it was solved in the following way.
I disassembled the router (unscrewed 3 antennas, removed 4 rubber legs, unscrewed 4 screws under them, opened plastic hood, pulled out PCB, unscrewed 6 small screws and removed the flat shield).
I measured resistance between the terminals of "Reset" button. It was zero Ohms in ON position and about 13 Ohms in OFF position. 13 Ohms seemed to be very low. One terminal of the button was soldered to large grounded area, the second terminal was soldered to the small pad that looked like island inside the mentioned large grounded area. It was surrounded by narrow path of insulative solder mask. I found under 40x magnification that there were tiny dotted lines of migrated solder across the solder mask. I cleaned them using cotton wool and alcohol. After that resistance between the button terminals rose up to 4.7 kOhms. I assembled the router and found that the problem disappeared.

Nice work. Let me guess your a licensed Ham operator like myself ? Back when we fixed or own stuff by hand..