I have the TL-WR841N v13 router. Several months ago I successfully flashed it from stock firmware to OpenWRT 23.05 via TFTP. Today I tried to flash another image (some extra packages included) which I built using image builder tool. But flashing it has made the router not working. It looks it boots (fast flashing system LED, then slow flashing system LED and then it stuck with the system LED still on). No reboot loop. The device do not respond to any activity on any of the ethernet ports, they are all dead. I decided to try to reflash it using TFTP again with the "official" OpenWRT ROM. It worked, the router downloaded the image (or at least I assume it downloaded it because of rapid flashing of the corresponding LAN LED) but after reboot it still didn't work. Symptoms are still the same - only the system LED is on and no activity is detected on any of the ethernet ports. Is there a solution for this? May this be a hardware failure? I do not care about this particular router much but I would really want to know what happen and why it has happen.
The push-button tftp recovery tends to be fairly reliable on these older TP-Link devices, based on your description there could be either of these two issues:
- image verification failing (wrong image (factory needed), wrong region code, etc.)
- the newly flashed image failing to boot up
Which it is, is hard to determine from the outside - connecting a USB to serial console adapter should give some clues, but unless you already own that, it's hardly worth the expense. .and TP-Link tends to make serial access intentionally difficult.
Hi @paul2no
best thing is to try reverting to factory image with TFTP method
you should download various versions on official tp-link site for your router and try one by one with tp-recovery.bin, or whatever filename your router want
why various versions?
some are containing u-boot (bigger files) so it is best to have them all 
Thank you for the replies. I've tried to TFTP the official image from TP-Link but it still didn't work. The router still behaves the same. In terms of serial console - will this thing do? Inside the router I found an unpopulated serial header and I should be able to solder pins there. I'm willing to try, at least I may learn something new.
Yes, it should work - but probably only on a linux host (as its FTDI chip is probably fake and rejected by FTDI's windows drivers).
The method reported on tp-link official pages is describing a TFTP recovery process not reliable. I personally tested something similar to: https://www.trishtech.com/2015/06/unbrick-tplink-wr740n-wifi-router/ or https://crosp.net/blog/hardware/unbrick-tp-link-wifi-router-wr841nd-with-tftp-wireshark/ and are working. You shall rename the original firmware file (the name may change model by model) and manually set your ethernet card IP as 192.168.0.66 (working for many tp-link models) or 192.168.0.68 (sometimes).