It is really strange.I support you contact your retailer.

Thanks for the advise, Stangang. It's going to take some time before I have the chance to take it to China to ask the street-seller for the possibility of repairing. I now use a WDR4300. Because of the poor wireless range I really miss the 840N. In the mean time I hope an expert could tip me a way to debrick it. What bother me is that it is now with a Broadcom ROM on a Atheros device. I tried TFTP there is no response. Please see the wiki device page:
http://wikidevi.com/wiki/TP-LINK_TL-WR840N_v1_(China_only%3F)

Hi Soma,I have seen the links you sent me.Unfortunately,I have found a link: http://wikidevi.com/wiki/TP-LINK_TL-WR840N_v1 .May 840 have the BCM chipest.Have a good luck.

stangang wrote

Hi Soma,I have seen the links you sent me.Unfortunately,I have found a link: http://wikidevi.com/wiki/TP-LINK_TL-WR840N_v1 .May 840 have the BCM chipest.Have a good luck.

My 840N is the china only version. Flashed the firmware with BCM chipset.

TP-LINK TL-WR840N v1 (China only?)

Atheros Atheros


TP-LINK TL-WR840N v1

BroadcomBroadcom

Oh no,that's strange because this china version only sells in china.Where did you buy this version?

During a business trip to China 3 years ago. Only £15 but running very well since. The WIFI range is butter than WDR4300. It does not worth much but felt pitty it is a such nice router.
If I power up the router the lights flashes once. Then some lights on 1 light off. I guess there is no hardware damage nut need to find a way to flash back the correct firmware.
So any advise?