[Tex/LaTex] Bold, upright greek symbol, \bm not working

Question

I seem to have a problem.
My task is to transfer several scanned equations into TeX equations.
Now my greek symbols won't accept to stay upright and italicized. \bm is somehow not working at all, \boldsymbol only making italicized version, \mathrm is powerless, \pmb only does italicized, I am starting to be at my wit's end and the internet seems to not help.

Code in TeXworks

\documentclass[a4paper,12pt,german]{article}

\usepackage{xcolor}
\usepackage{ngerman}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{bm}
\usepackage[OMLmathrm,OMLmathbf]{isomath}

\begin{document}

\section{Bild 1}
\begin{equation}
\bm{\kappa} \frac{\partial^2 T}{\partial x^2}=\frac{\partial T}{\partial t}
\end{equation}

\end{document}

Answer 1

The isomath package doesn't claim to make lowercase Greek letters upright and it doesn't.

If you want upright Greek lowercase, load upgreek:

\documentclass[a4paper,12pt]{article}

\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[ngerman]{babel}
\usepackage{xcolor}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{bm}
\usepackage{upgreek}
\usepackage[OMLmathrm,OMLmathbf]{isomath}

\begin{document}

\section{Bild 1}
\begin{equation}
\bm{\upkappa} \frac{\partial^2 T}{\partial x^2}=\frac{\partial T}{\partial t}
\end{equation}

\end{document}

By the way, the ngerman package is obsolete and deprecated. Use babel instead.