Then you need to verify the line.(source of the power) If you put line on the line connection of the switch and neutral to the other white wires in the box and to the neutral on the switch it should at least power up. Leave the load wire off just attach line and neutral it should at least power up if that part is correct.
Are we talking about the same switch?
If so if the switch powers up there is an blue LED that shines through this little hole (circled in red) next to the pull out isolation switch. It is usually programmable to be either on when switch on or off when switch off. It is also what blinks when you are pairing the light to smartthings.
Also there is an air gap isolation switch next to the LED that should be pushed in. If it is pulled out the supply power has been removed from the switch.
Also just to be sure, this IS the only switch in the circuit correct?
I am guessing the assumption about which wire is line, is not correct. Run to a store today or order one if you can wait. Get a meter or non contact voltage detector. Figure out which wires are going where? You can’t trust wires colors or anything. Need to figure it out.