GreenWorks Lawn Mower Review: Pro 21-Inch 80V Lithium Ion ... The mower is quite easy to start — most GreenWorks mowers usually are. You just push the start button, pull the bail switch and voila, it’s running. Be sure that the battery is sufficiently charged and inserted into the mower correctly. To close the back handle of the mower, press and hold the green safety lock out button.