#4 No… The printer wont catch on fire because the z-axis motor is cycling on it’s torque limit.
When the bed is at the bottom and you turn on the printer it will try to move the bed down but since its already at the bottom it becomes physically stopped by the end plates. Since the printer doesn’t know where home is it tries to continue its startup code by moving the bed down. When it reaches the end plates you will hear it making a terrible sound. It’s the z-axis motor stopping and starting rapidly due to reaching its designed torque limit or its the belt slipping if the belt is loose. They are limited by torque output so they wont break anything if bound up.