Beamer titlepage without the headline/footline template

Question

I am trying to duplicate a given corporate design as beamer theme.

A far, I was able to reproduce most of the settings for the normal slides.

Now I am working on the title page, which has a complete different design, mostly with other logos and a customized header and footer. My problem: how do I get rid of the headline and footline template just for the title page? Using \begin{frame}[plain] isn't a real option, because, when you forget to add the [plain], you'll get both logos and so on.

In my MWE I present the same problem by removing the nav symbols from just the title page.

EDIT

I added three example templates headline, footline and title page to this example. I want to get rid of the two logos A and B from the title page.

\documentclass{beamer}
\usepackage{graphicx}

\usetheme{Berlin}

\title{Some ordinary title}
\subtitle{And another title}
\author{I. T. Sme}
\date{Not Long Ago}

%% This would remove the nav symbols from all slides, which I don't
%% want.
% \setbeamertemplate{navigation symbols}{}

\setbeamertemplate{headline}{%
  \includegraphics[width=.1\linewidth]{example-image-a}
}
\setbeamertemplate{footline}{%
  \hfill\includegraphics[width=.1\linewidth]{example-image-b}
}

%% I'd love to get rid of the logos A and B and the navigation
%% symbols, but setting the templates temporary to {} does have no
%% effect.
\setbeamertemplate{title page}{%
  \setbeamertemplate{headline}{}%
  \setbeamertemplate{footline}{}%
  \setbeamertemplate{navigation symbols}{}%  
  \centering\includegraphics[width=.1\linewidth]{example-image-c}%
  \vskip1cm
  \begin{center}
    \inserttitle\\
    \insertsubtitle\\
    \insertauthor,\ \insertdate
  \end{center}
  \vfill%
}

\begin{document}
  \begin{frame}
    \titlepage{}
  \end{frame}

\begin{frame}
  \frametitle{First real slide}
  This is a normal slide with normal headline and footline.
\end{frame}
\end{document}

What must I write into my \defbeamertemplate{title page} to temporary remove the headline/footline from that titlepage?

There is a similar question, in which the answer was given, to define the headline/footline in dependency of the page number: no headline for page 1, footline of page > 1. This is also not an option for me, as the corporate design supplies from one up to three titlepages. :-(

If there is any other chance, to test from within the footline template, if the actual page is a title like page, that would be great.

Answer 1

As Sam Carter is no more active on TeX.SE, she nevertheless was so friendly, to point out to a solution, she gave on topanswers.xyz.

I repeat her answer here, with three minor fixes.

Please note: this is an answer from SAM CARTER! All the credit and the glory belong to her!

\documentclass{beamer}

\defbeamertemplate{footline}{special footline}{%
  special footline
}

%% EDIT from me: In my case it worked, when I changed \setbeamertemplate
%% to \defbeamertemplate
%\setbeamertemplate{footline}{%
\defbeamertemplate{footline}{%
  normal footline
}


\makeatletter
\def\ps@navigation@titlepage{%
%% EDIT from me: the second braces need to be optional braces
%  \setbeamertemplate{footline}{special footline}
  \setbeamertemplate{footline}[special footline]
  \@nameuse{ps@navigation}
}
\addtobeamertemplate{title page}{\thispagestyle{navigation@titlepage}}{}
\makeatother

\AtBeginSection[]{%
\begingroup
%% EDIT from me: again, there need to be optional braces
%\setbeamertemplate{footline}{special footline}
\setbeamertemplate{footline}[special footline]
\begin{frame}
  \sectionpage
\end{frame}
\endgroup
}

\apptocmd{\tableofcontents}{\thispagestyle{navigation@titlepage}}{}{}

\begin{document}
\maketitle

\begin{frame}
\tableofcontents
\end{frame}

\section{abc}
\begin{frame}
\frametitle{abc}
cde
\end{frame} 
\end{document}

Thank you Sam!