My most hated error message:
1. could not get com port recognized (saw as usb): went into device manager and checked for “show hidden devices”
2. code ran properly when nano attached to usb but did not work when not attached to usb: the fix for this was to re-arrange some pins (27 vs 30?). When using an external power source only (and not usb), then pins must be re-arranged.
3. bluetooth malfunctioning at times by going offline, robot only going in circles: had tried 9V and 4 AA alkaline, ended up ordering Lithium Ion 18650 2600mAh flat top batteries