TL-WR841ND V 7.2 bricked after go back to original firmware

Installing and Using OpenWrt
1

Hi all! I tried to go back to the original firmware copying the factory firmware into the tmp directory and installing it. Now the router is bricked! All leds (except wifi that still off) blink simultaneously. Connetting via serial with putty I have the following result:

▒▒▒$▒A▒VALUE 1 = 0xf, 2 = 0x10 [0x0: 0x1f]
`▒j     5
         Z▒▒▒▒▒0x100000ff
sector count = 64
Flash:  4 MB
U▒▒▒default environment

RK▒▒ɥ▒▒5
        Out:   serial
Err:   serial
▒▒▒   ag7240_enet_initialize...
No valid address in Flash. Using fixed address
No valid address in Flash. Using fixed address
UK▒▒▒▒MDC CFG Value ==> 4
: cfg1 0xf cfg2 0x7014
Y
 ▒▒▒҂▒Һ2▒09:0b:ad
Y
 ▒▒5
    Virian MDC CFG Value ==> 4
: cfg1 0xf cfg2 0x7214
Y+▒▒▒҂▒Һ2▒09:0b:ad
ATHRS26: resetting s26
PJ5%▒▒▒▒6 reset done
Y+▒▒5
     eth0, eth1
Autobooting in 1 seconds
▒$▒▒ѥ▒▒▒image at 9f020000 ...
   Uncompressing Kernel Image ... Error: Bad gzipped data
GUNZIP ERROR - must RESET board to recover

Resetting...C▒H▒▒▒▒с1.1.4 (Jan 30 2012 - 18:33:40)

AP99 (ar7241 - Virian) U-boot
DRAM:
sri
ar7240_ddr_initial_config(182): virian ddr1 init
▒▒▒$▒A▒VALUE 1 = 0xf, 2 = 0x10 [0x0: 0x1f]
▒j      5
         Z▒▒▒▒▒0x100000ff
sector count = 64
Flash:  4 MB
U▒▒▒default environment

RK▒▒ɥ▒▒5
        Out:   serial
Err:   serial
▒▒▒   ag7240_enet_initialize...
No valid address in Flash. Using fixed address
No valid address in Flash. Using fixed address
UK▒▒▒▒MDC CFG Value ==> 4
: cfg1 0xf cfg2 0x7014
Y
 ▒▒▒҂▒Һ2▒09:0b:ad
Y
 ▒▒5
    Virian MDC CFG Value ==> 4
: cfg1 0xf cfg2 0x7214
Y+▒▒▒҂▒Һ2▒09:0b:ad
ATHRS26: resetting s26
PJ5%▒▒▒▒6 reset done
Y+▒▒5
     eth0, eth1
Autobooting in 1 seconds
▒$▒▒ѥ▒▒▒image at 9f020000 ...
   Uncompressing Kernel Image ... Error: Bad gzipped data
GUNZIP ERROR - must RESET board to recover

Resetting...C▒H▒▒▒▒с1.1.4 (Jan 30 2012 - 18:33:40)

AP99 (ar7241 - Virian) U-boot
DRAM:
sri
ar7240_ddr_initial_config(182): virian ddr1 init
▒▒▒$▒A▒VALUE 1 = 0xf, 2 = 0x10 [0x0: 0x1f]
▒j      5
         Z▒▒▒▒▒0x100000ff
sector count = 64
Flash:  4 MB
U▒▒▒default environment

RK▒▒ɥ▒▒5
        Out:   serial
Err:   serial
▒▒▒   ag7240_enet_initialize...
No valid address in Flash. Using fixed address
No valid address in Flash. Using fixed address
UK▒▒▒▒MDC CFG Value ==> 4
: cfg1 0xf cfg2 0x7014
Y
 ▒▒▒҂▒Һ2▒09:0b:ad
Y
 ▒▒5
    Virian MDC CFG Value ==> 4
: cfg1 0xf cfg2 0x7214
Y+▒▒▒҂▒Һ2▒09:0b:ad
ATHRS26: resetting s26
PJ5%▒▒▒▒6 reset done
Y+▒▒5
     eth0, eth1
Autobooting in 1 seconds
▒$▒▒ѥ▒▒▒image at 9f020000 ...
   Uncompressing Kernel Image ... Error: Bad gzipped data
GUNZIP ERROR - must RESET board to recover

Resetting...C▒H▒▒▒▒с1.1.4 (Jan 30 2012 - 18:33:40)

AP99 (ar7241 - Virian) U-boot
DRAM:
sri
ar7240_ddr_initial_config(182): virian ddr1 init
▒▒▒$▒A▒VALUE 1 = 0xf, 2 = 0x10 [0x0: 0x1f]
▒j      5
         Z▒▒▒▒▒0x100000ff
sector count = 64
Flash:  4 MB
U▒▒▒default environment

RK▒▒ɥ▒▒5
        Out:   serial
Err:   serial
▒▒▒   ag7240_enet_initialize...
No valid address in Flash. Using fixed address
No valid address in Flash. Using fixed address
UK▒▒▒▒MDC CFG Value ==> 4
: cfg1 0xf cfg2 0x7014
Y
 ▒▒▒҂▒Һ2▒09:0b:ad
Y
 ▒▒5
    Virian MDC CFG Value ==> 4
: cfg1 0xf cfg2 0x7214
Y+▒▒▒҂▒Һ2▒09:0b:ad
ATHRS26: resetting s26
PJ5%▒▒▒▒6 reset done
Y+▒▒5
     eth0, eth1
Autobooting in 1 second

Can I recover it?

2

That's the point where you should be able to interrupt the bootloader by typing tpl and to upload and flash a new factory image via tftp; however it's very likely that you destroyed your ART partition before (bricking wireless for good).

3

I've got the same problem here, i am using a Arduino to connect since i cant get my old DKU-2 to work with windows 10. However i try to type tpl as fast as i can but it keeps looping. I am not sure the unreadable characters should be there, but is looks like they are all on the same places as to maurobers output. Does anyone have any tips to resolve this problem?

▒$▒▒ѥ▒▒▒image at 9f020000 ...
   Uncompressing Kernel Image ... Error: Bad gzipped data
GUNZIP ERROR - must RESET board to recover

Resetting...C▒H▒▒▒▒с1.1.4 (Sep  3 2010 - 12:35:51)

AP99 (ar7241 - Virian) U-boot
DRAM:
sri
ar7240_ddr_initial_config(133): virian ddr1 init
▒▒▒$▒A▒VALUE 1 = 0xf, 2 = 0x10 [0x0: 0x1f]
32 MB
Z▒▒▒▒▒0x100000ff
sector count = 64
Flash:  4 MB
U▒▒▒default environment

RK▒▒ɥ▒▒5
        Out:   serial
Err:   serial
▒▒▒   ag7240_enet_initialize...
No valid address in Flash. Using fixed address
No valid address in Flash. Using fixed address
UK▒▒▒▒MDC CFG Value ==> 4
: cfg1 0xf cfg2 0x7014
Y
 ▒▒▒҂▒Һ2▒09:0b:ad
Y
 ▒▒5
    Virian MDC CFG Value ==> 4
: cfg1 0xf cfg2 0x7214
Y+▒▒▒҂▒Һ2▒09:0b:ad
ATHRS26: resetting s26
PJ5%▒▒▒▒6 reset done
Y+▒▒5
     eth0, eth1
Autobooting in 1 seconds
4

The distortions suggest bad connectivity (particularly for GND).

5

I just did the soldering again, this time using some pin connectors en shorter cables.
The distortion remains, but i can send the tpl signal now. Will it hurt when i upload the new firmware with this distortion?

6

I solved using 2 pc, and all work fine. First pc to run Putty and the second to run TFTP64
All work fine! Totaly recovered as original. Thanks

7

Ignore the unreadable characters, is not a problem! Follow the instructions using copy past. Be careful because Arduino uno work at 5V and some version of the router work at 3.3V and you can destroy it

8

I use resistors to shift the voltage on the transmit channel of the arduino down to around 3.3V.
I did not have any succes yet with unbricking. It is not always i can succesfully send the tpl signal. Sometimes it works but most of the time it won't. And after it finally worked the modem goes haywire after a few secconds returning a lot of garbage and wont accept any command to be transmitted.

9

what version do you have?