Hello!
After unsuccessfully upgrading from 15.01 to 18.06.02, my router ended up bricked. Power LED is the only one shining in addition to LAN port, when it is plugged to a PC. I tried various methods that involved holding reset button such as 30 30 30, but with no results.
After that I found this -> https://crosp.net/blog/hardware/unbrick-tp-link-wifi-router-wr841nd-with-tftp-wireshark/ guide, however I can't seem to get tftpd32 to upload recovery file. Up to that point, everything is going fine, tftp packets with read request appear in wireshark, but even with holding reset/wps button, nothing appears in tftpd, no matter how long the button is held. I tried various similar guides that recommended adding tftpd to firewall exceptions, disabling firewall, disabling wireless connections, also with no success. Am I missing something? Cheers!