Read Measuring Vibration in ArduPilot documentation. Interesting if Betaflight has similar means/tool for measuring vibrations. Vibration Damping.

Read Firmware Limitations on AutoPilot Hardware. RAM Limitations section shows possible symptoms when flight controller has insufficient RAM. This symptoms, like compass calibration not starting or logging not starting or parameters download in Ground Control Station are slow are interesting.

in Mission Planner’s STATUS tab, you can monitor the “freemem” status for current free RAM

Read Connect Mission Planner to AutoPilot.

Read Diagnosing some common problems using Logs.

Read Learning the ArduPilot Codebase.

Read Battery Monitors (aka Power Monitors/Modules).