If your hardwired smoke alarm keeps going off, it could be because the backup battery needs replacing. When replacing the battery doesn’t stop your smoke alarm from beeping, try holding the reset button for 15 to 30 seconds or removing dust from the openings in the alarm. If it continues to chirp, it could be faulty and require replacement.

Yes, it is possible. An electrical fire can break out if the compressor has inadequate ventilation. When it overheats but doesn't have a proper thermal cutout, this can cause the motor to short-circuit and catch fire. This risk is exacerbated if flammable materials, like dust and fallen leaves, are clogging the unit. The compressor overheating won't start a fire by itself, but poor maintenance and installation can increase the risk once it hits its breaking point and short-circuits.

Baking soda is an effective fire reduction method. However, flour and baking powder are very dangerous around flames. Flour is flammable and it can also conduct electricity. The combination can cause serious injury from electrical shock and worsen the situation by adding fuel to the fire. Baking powder is also not an option as it's also highly flammable. 

The primary disadvantage of a ventless fireplace is that it doesn’t have an exterior venting system. This means that the byproducts from combustion are emitted into your home, which raises some safety concerns. In addition, ventless gas fireplaces produce moisture as they burn—and if there’s no ventilation, you could end up with a mold problem.