The repairs were reported on the press and on TV by spokepersons for the technician as both, having being "disconnected" and having the "fuse removed".
The most sensible scenario seems to be: Pilot informs PAX that he is not proceeding with (first) T/O because a 'red light warning indicator came on' and he is unsure about what it is and wants it checked out by techs, they return to gate (or service area) and repair tech and pilot decide the fault indicated is with the heater to assist probe readings in some weather conditions. Since no danger of those weather conditions exist, they decide in compliance with manual procedures to disconnect it and both signed the plane fit-to-fly. The Pilot informs PAX that it was a fault with a "heat sensor" that was fixed already and they were ready to take-off.
What 'warning light' the pilot was talking about is, of course, not clearly stated anywhere.