What kind of cooktop is it?
New York Appliance Desk books cooktop and microwave repair for Manhattan, Brooklyn, Queens and the Bronx kitchens: gas rangetops, glass-top electric, induction, and microwaves mounted over the range, built into a wall or sitting in a drawer under the counter.
Gas burners that click and won't catch
Each burner lights from a spark igniter fed by a spark module, triggered by a switch behind the knob. A boil-over that soaked the igniter, a burner cap that isn't seated flat, or a cracked ceramic igniter are the usual causes. Clicking that won't stop even with every knob off points to a wet or failed switch. Many pro-style rangetops add an automatic reignition system that relights the flame if it goes out, and that system has its own module.
Glass-top electric that won't heat
Radiant elements sit under the glass and run off infinite switches or touch controls. A dead zone is usually the element, its switch or a limiter, and on touch models the control board. A scorched terminal block behind the cooktop can cut power to several zones at once.
Induction that flashes or cuts out
Induction heats the pan directly with a magnetic field from a coil under the glass. Nothing glows, so nothing burns out the way a coil does. Faults come from the pan (not magnetic enough, or too small for the ring), the cooling fan, a temperature sensor, or the power board that drives the coils. On overheating shutdowns the tech checks the air intake under the cooktop first, especially where a drawer was built tight below it.
What about microwaves?
A microwave that runs but doesn't heat usually has a failed magnetron, a high-voltage diode or capacitor, or a blown fuse. One that does nothing when the door shuts often has a failed door switch. These parts store high voltage even unplugged. Microwave repair is a tech's job, never a home project.
Over-the-range microwaves also act as the range hood. If the fan or light works but the oven doesn't, or the reverse, say which on the call. Drawer microwaves add their own drawer motor and tracks.