Clone the project, and realize that whatever repo managing system they started using 3 years ago requires setup steps not in the README and breaks everything at the slightest touch.
Build the currently relevant project in whatever build system they started using 3 years ago (CMake is quite nice).
Fix my vimrc to be compliant with whatever tabbing they use.
Realize that for some reason, someone made a commit in the file I'm reading that uses 3 space tabs. And worse, someone approved that PR.
Make changes via vim.
Debug via print because setting up gdb or JTAG on embedded systems is usually more effort than its worth.
Realize it's a timing issue and reluctantly go find the JTAG debugger.