Intention (mens rea) is not a get out of jail free card, it just changes the nature of the crime and charges you get convicted off.

If you run someone over on purpose you get convicted of murder. If You do it by driving recklessly you get convicted of culpable homicide.

The only time you get off with nothing is if it is determined to be an accident.

As they always say: ignorance of the law is no excuse. Running a dangerous machine prevents you from claiming you had no idea the machine was dangerous.

Especially if they kept telling us how dangerous the machine is.