A robotic lawn mower's navigation glitches after its mainboard is repaired. The technician swaps the navigation sensor, the glitch remains, and is out of ideas. What does the section teach?

Select one answer.

• Nothing — replacing the glitching navigation sensor is the correct and complete repair for a navigation glitch, so if the glitch remains the replacement sensor must itself be defective and a second replacement is the right next step. A symptom points straight at the part that shows it, the swap-the-symptom argument board repair leans on — a navigation glitch lives in the navigation sensor, so replacing that sensor is the direct fix, and a glitch that survives the swap simply means the new sensor was also bad, making another sensor the logical next move rather than any wider investigation of sources or paths.
• Only the firmware — a glitch that survives a sensor swap is always a software fault, so reflashing the mower's firmware, not any hardware investigation, is what the persistence points to.
• The glitch is an interference chain, and only naming all three parts solves it: the mainboard the repair disturbed is the likely source, the shared ground or nearby routing is the coupling path, and the navigation sensor is only the victim — so swapping the victim changes nothing, and the work belongs at the source and the path the repair opened.
• The sensor cable — the navigation sensor's wiring was disturbed during the repair, so reseating or replacing that one cable, not considering any source or path, resolves the glitch.