Start at the DB board: what a trip is actually telling you
A single MCB tripping repeatedly means one circuit is overloaded or has a faulty appliance or fixture on it. An RCD tripping means electricity is leaking to earth somewhere, classically through a failing water heater element, a washing machine, or moisture in an outdoor fitting. The whole board going dark while your neighbours still have power usually points to the main incomer or the utility's side of the connection, which is not something any private electrician is allowed to open.
UAE boards have a few local quirks worth knowing before trouble starts. Water heaters usually have their own switches, sometimes on the board and sometimes on the bathroom wall, and each split AC unit typically has a dedicated isolator. Older flats often carry a second small board for the heaters alone. Ten minutes spent flipping breakers one by one and writing what each controls on the board's door turns your next fault call from a vague description into a precise one, and shortens the electrician's paid diagnosis time accordingly.