So here's my problem: I am trying to use \cite{} in a beamer. I would like the output of \cite{{AB_00} to be either something like [1] or Author A \& Author B, which is essentially what I've written in brackets. Below is my code and its output:
\documentclass[10pt]{beamer}
\mode<beamer>{\usetheme[hideothersubsections, right, width=22mm]{Goettingen}}
\usepackage[english]{babel}
\usepackage{biblatex}
\begin{document}
\begin{frame}
Test \cite{AB_00}
\end{frame}
\begin{frame}
\begin{thebibliography}{}
\bibitem[Author A \& Author B]{AB_00} A \& B 2000
\end{thebibliography}{}
\end{frame}
\end{document}
Any help or suggestion is greatly appreciated.
P.S. I've tried turning my code into a m.w.e. If however something is unclear, please let me know so I can try clearing it up.

thebibliographycan not be used withbiblatexas it is completely incompatible with that package. See https://tex.stackexchange.com/q/277567/35864 – moewe Dec 22 '18 at 16:10biblatex, removethebibliographyand write a.bibfile for your entries (see also https://tex.stackexchange.com/q/13509/35864). If you want to use a manual bibliography, just dropbiblatex(remove the\usepackage{biblatex}in the MWE). See also https://en.wikibooks.org/wiki/LaTeX/Creating_Citations_and_Bibliographies, https://en.wikibooks.org/wiki/LaTeX/Bibliography_Management, https://en.wikibooks.org/wiki/LaTeX/Manually_Managing_References and https://en.wikibooks.org/wiki/LaTeX/Bibliographies_with_biblatex_and_biber – moewe Dec 22 '18 at 16:14