The answer to 'panel upgrade burning smell' is that a burning smell coming from your electrical panel is a serious issue that requires immediate attention. This could indicate overheating, loose connections, or other electrical problems that pose a fire hazard. Do not attempt to inspect or work on the panel yourself - this is a job for a licensed and experienced electrician.
A burning smell from your electrical panel is not something to ignore. It's a clear sign of an electrical problem that needs professional diagnosis and repair to ensure your safety and prevent a potential fire. Call an electrician right away to inspect the panel and identify the underlying cause.