Original Image restored and a few small changes

Question

I am new to LaTeX. I want to add a university logo below the first page (as shown in the photo below). Also, I want to change the color of box (I don't like the color red).

Any idea please.

Tex file:

\documentclass[9pt,]{beamer}
\usetheme{Warsaw}
\usepackage[utf8]{inputenc}
\usepackage[french]{babel}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsthm}
\usepackage{dsfont}
\usepackage{color}
\usepackage{pifont}
\usepackage{tikz}
\usepackage{colortbl}
\usepackage{fancybox} 
\setcounter{MaxMatrixCols}{50}
\usepackage{amsmath, amssymb, mathrsfs}
\setbeamertemplate{navigation symbols}{\insertframenumber~/~\inserttotalframenumber}
\usepackage{graphicx}
%\usecolortheme{beaver}
\definecolor{UBCblue}{rgb}{0.0, 0.5, 1.0}
\usecolortheme[named=UBCblue]{structure}
\setbeamercolor{block title}{use=structure,fg=white,bg=UBCblue!75!black}
\setbeamercolor{block body}{use=structure,fg=black,bg=white!20!white}
\title{Title}
\author{Name} 
 \institute{University}
\date{2020}
\begin{document}
\begin{frame}[plain, noframenumbering]
  \titlepage
\end{frame}
\begin{frame}
\begin{alertblock}{Theorem:}
ABCDEFGH
\end{alertblock}
\end{frame}
\end{document}

Result

Logo:

Answer 1

Adding the logo

You can add your university logo at any field of the title page. In your case you want it below the date so you can change the \date command as follows:

\date{2020\par \includegraphics[width=0.2\linewidth]{JOoML.png}}

or even better (thanks to @Rmano comment)

\date[2020]{2020\par \includegraphics[width=0.2\linewidth]{JOoML.png}} 

so you have the short date form 2020 if it is needed in the format elsewhere.

You can also add a small sized logo at each page of your presentation using

\logo{\includegraphics[width=0.5cm]{JOoML.png}} % optional

Changing the block color

You can change the color of any block by \setbeamercolor command then adding the name of the block and the color of your choice of the background and foreground. Here is an example you can use

\setbeamercolor{block title alerted}{bg=green!50,fg=black}
\setbeamercolor{block body alerted}{bg=yellow!50,fg=black}

The output would be

Here's your full code:

\documentclass[9pt,]{beamer}
\usetheme{Warsaw}
\usepackage[utf8]{inputenc}
\usepackage[french]{babel}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsthm}
\usepackage{dsfont}
\usepackage{color}
\usepackage{pifont}
\usepackage{tikz}
\usepackage{colortbl}
\usepackage{fancybox} 
\setcounter{MaxMatrixCols}{50}
\usepackage{amsmath, amssymb, mathrsfs}
\setbeamertemplate{navigation symbols}{\insertframenumber~/~\inserttotalframenumber}
\usepackage{graphicx}
%\usecolortheme{beaver}
\definecolor{UBCblue}{rgb}{0.0, 0.5, 1.0}
\usecolortheme[named=UBCblue]{structure}
\setbeamercolor{block title}{use=structure,fg=white,bg=UBCblue!75!black}
\setbeamercolor{block body}{use=structure,fg=black,bg=white!20!white}
\title{Title}
\author{Name}
\institute{University}
%
%
\date[2020]{2020\par \includegraphics[width=0.2\linewidth]{JOoML.png}} % <--- modified
\logo{\includegraphics[width=0.5cm]{JOoML.png}} % <--- added
%
\setbeamercolor{block title alerted}{bg=green!50,fg=black} % <--- added
\setbeamercolor{block body alerted}{bg=yellow!50,fg=black} % <--- added
%
\begin{document}
    \begin{frame}[plain, noframenumbering]
        \titlepage

    \end{frame}
    \begin{frame}
        \begin{alertblock}{Theorem:}
            ABCDEFGH
        \end{alertblock}
    \end{frame}
\end{document}