Describe the point where it stops
Note whether the door never starts down, reverses partway or returns upward near the floor. Include any visible indicator light pattern. Do not keep operating a door that is crooked, has a loose cable or shows signs of mechanical damage.
Keep the area clear without changing the mechanism
People, pets and stored objects should be out of the travel area. Do not move a damaged door by hand, alter force settings or defeat the sensors. A closing problem may involve the door, the opener or their interaction.
Explain how the garage is used
Mention whether the opening can be secured and whether another entrance exists. Keep the opener model details available if safely accessible. Ask how the technician will distinguish an accessory fault from a mechanical problem before replacing parts.
Your questions
Does reversing always mean bad sensors?
No. Different causes can produce similar behavior, so the fault needs assessment before parts are selected.
Should I hold the button until it closes?
Do not use a control workaround to conceal an unexplained safety or movement problem. Follow the equipment instructions and arrange service.