We made it!
After thousand of tests, passing by a serial tftp boot, trying jtag reprogramming we finally get back the wr841nd (ver.8.1) to life!
We followed an OpenWRT guide that you can find over here
Well… we disassembled the flash of another working router with a very small soldering iron tip (all the merit goes to Edo).
Then we connected to the serial of the router via an arduino adapter. Doing this we cuold connect to uboot (remember the “tpl” keys for getting to the uboot console!!).
From the console we dumped all the files of the flash into the ram with the command:
1 cp.b 0x9f000000 0x81000000 0x3effff
The command is: copy the content of the flash (0x9f000000) to the ram (0x81000000) for the lenght (0x3effff)
Then we reassembled the old broken flash and copied all back in that one with the command:
1 cp.b 0x81000000 0x9f000000 0x3effff
And doing this we restored uboot in the broken flash. After this we reinstalled OpenWRT via the tftp server mode with the following commands:
1 erase 0x9f020000 +0x3c0000C
1 tftpboot 0x81000000 openwrt.binC
1 cp.b 0x81000000 0x9f020000 0x3c0000C
1 bootm 0x9f020000
Finally we had a working router!