Hi

Please let me know what make the mower is? As long as the mower has power and you are pressing the safety button before the starter lever, then it should start. I know these are obvious thing, but if you are doing this, then the mower may be faulty. You ask this question under Electric Corded mowers, so there would not be any safety keys or batteries that you would get with a cordless mower.

Below are some reasons for electric mowers not starting (as this is a new mower, some are not applicable)

Tripped circuit breaker or blown fuse
Faulty power outlet
Damaged or unplugged power cord
Worn out or defective motor
Overheated mower requiring cooldown
Safety switch not engaged
Faulty starter switch or button
Accumulation of grass and debris obstructing blade movement
Electrical wiring issues within the mower

Thanks
Mark