per the instructions in ``u-boot\verb0_0reflash'' in its section ``Installing

u-boot to your router'', which reads:

\begin{quotation}

  \begin{enumerate}

    \item Install and configure any TFTP server on your PC (tftp-hpa).

       Set a fixed IP address on your PC \ldots and connect it to the router,

       using RJ45 network cable \ldots

 \item Connect USB to UART adapter to the router and start any application to

   communicate with it, like PuTTY. \ldots

   \item Power on the router, wait for a line like one of the following and

     interrupt the process of loading a kernel:

\begin{verbatim}

    Autobooting in 1 seconds (for most TP-Link routers, you should enter tpl at this point)

    Hit ESC key to stop autoboot: 1 (for 8devices Carambola 2, use ESC key)

    Hit any key to stop autoboot: 1 (for D-Link DIR-505, use any key)

\end{verbatim}

\item   Set ipaddr and serverip environment variables:

\lstset{tabsize=2}

\begin{lstlisting}

    hornet> setenv ipaddr 192.168.1.1

    hornet> setenv serverip 192.168.1.2

\end{lstlisting}

  \end{enumerate}

\end{quotation}

At this point in the installation process, hitting a key failed to interrupt

the boot process and yield the \verb0hornet>0 prompt.  For the investigator,

this became a moment of consideration: is this 

However, the investigator was only able to read data from the serial port;

the investigator was unable to send key events via the serial port so the

U-Boot console could not be accessed in that way.  The investigator did find

another way of accessing the U-Boot console, though, which was used to

complete the U-Boot installation and verification.  The likely issue with the

serial port was initial mis-wiring of the serial connector, causing the

receive pin to be permanently disabled.  Here are the steps the investigator

tried, including the alternate method of installation that did not require

the serial console: