There is a bed leveling wizard in Octoprint that works well. It steps you through the process, moving the bed and printhead to four different locations and you can make adjustments with the screws with the machine on.
You don’t need to have the power on for current to flow when moving the bed or print head. The steppers will act as a generator. I noticed this some time back on my CNC when I moved the spindle…the leds on the controller board light up when the stepper motors turn as I’m moving the spindle.