Bash – Exiting `reverse-i-search`

From the man page :

   -X   Send the specified command to a running screen  session.  You  can
        use  the  -d or -r option to tell screen to look only for attached
        or detached screen sessions. Note that this command  doesn't  work
        if the session is password protected.

You can do :

        screen -X -S <sessionid> kill

The "i" in "reverse-i-search" stands for "incremental" so it searches as you type. If you want it to wait until you finish typing you can use history-search-backward (not bound) or non-incremental-reverse-search-history (bound to Meta-p). To use those functions, you type the text first then press the keystroke that invokes the function.

I have history-search-backward bound to PgUp and ``history-search-forward` bound to PgDn.

To terminate a search press Esc, as you know. To abort a search leaving an empty command line, press Ctrl-G.