# Include equation align inside block in Beamer

I have the following Beamer document, but I get errors in the frame shown. Any ideas what the problem might be and how to solve it?

\documentclass{beamer}

\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[american]{babel}
\usepackage{amsmath,amssymb,amsthm}
\usepackage{tikz}

\mode<presentation>
{
\usetheme{default}      % or try Darmstadt, Madrid, Warsaw, ...
\usecolortheme{default} % or try albatross, beaver, crane, ...
\usefonttheme{default}  % or try serif, structurebold, ...
\setbeamertemplate{caption}[numbered]
}

\usepackage{sourcesanspro}
\usepackage[amssymb,amsfonts]{concmath}
\usefonttheme[onlymath]{serif}

\usepackage{graphicx}
\graphicspath{ {images/} }
\usepackage{eso-pic}

\renewcommand{\emph}[1]{{\usebeamercolor[fg]{structure}#1}}

\renewcommand{\O}{\mathcal{O}}
\newcommand{\ZZ}{\mathbb{Z}}

\begin{document}

\begin{frame}{Group structure}
\begin{block}{Torsion structure}
Let $E$ be defined over an algebraically closed field $\bar{k}$ of
characteristic $p$.
\begin{align*}
E[m] \simeq\quad& \ZZ/m\ZZ\times\ZZ/m\ZZ  &\text{if p\nmid m,}\\[1em]
&\ZZ/p^e\ZZ & \text{\emph{ordinary} case,}\\[-1.7em]
E[p^e] \simeq\Biggl\{& \\[-1.7em]
\begin{cases}
&\{\O\} & \text{\emph{supersingular} case.}
\end{cases}
\end{align*}
\end{block}
\end{frame}

\end{document}


The first error is that \text puts its content in text mode so you need $ to get back to math  \text{if$p\nmid m\$,}

The second error is that cases is a two-column alignment so you can only have one & you could use
           \begin{cases}

which has one & so error free but a cases alignment with only one row doesn't serve any purpose, so I am not sure of the intended layout there.