DIAGNOSIS The main control board or power supply has likely failed, but the fan might still be getting partial power, hence the hum. It's a hardware fault.
FIX First, check the obvious: ensure the power cord is fully plugged into both the wall outlet and the port on the back of the Air Pro (it can work loose). Try a different, known-working wall outlet. If there's truly no life in the display, unplug it and perform a hard reset: hold the 'Power' and 'Fan Speed' buttons down simultaneously for 15 seconds while it's unplugged. Then plug it back in. This sometimes reboots a locked-up controller.
IF THAT DIDN'T WORK If the display remains dead, the internal 12V DC power supply (which converts wall power for the logic board and display) is the prime suspect. This is not a user-repairable component. Your only path is to contact Molekule support for warranty service or a replacement unit.
HEADS UP That faint hum means some circuitry is still live. Do not attempt to open the sealed main housing to investigate—you'll void the warranty and there are no user-serviceable parts inside. The repair requires specific tools and knowledge of the sealed system.