A surgical instrument , comprising: an end effector (300; 501); a firing drivetrain configured to transmit at least one motion to the end effector; an electric motor operably coupled to the firing drivetrain, wherein the electric motor is configured to generate a mechanical output to motivate the firing drivetrain to transmit the at least one motion to the end effector; and a controller , comprising: a processor ; and a memory storing program instructions; characterized in that the program instructions, which when executed by the processor, cause the processor to operate as follows: in response to an acute failure which causes the firing drivetrain to operate at less than optimal performance levels, to activate a safe mode in which the processor modulates the mechanical output of the electric motor to limit the speed of the firing drivetrain and allow the electric motor to complete the firing sequence; and in response to a catastrophic failure which renders the firing drivetrain inoperable, to activate a bailout mode in which the processor disables the electric motor . an end effector (300; 501); a firing drivetrain configured to transmit at least one motion to the end effector; an electric motor operably coupled to the firing drivetrain, wherein the electric motor is configured to generate a mechanical output to motivate the firing drivetrain to transmit the at least one motion to the end effector; and a controller , comprising: a processor ; and a memory storing program instructions; characterized in that the program instructions, which when executed by the processor, cause the processor to operate as follows: in response to an acute failure which causes the firing drivetrain to operate at less than optimal performance levels, to activate a safe mode in which the processor modulates the mechanical output of the electric motor to limit the speed of the firing drivetrain and allow the electric motor to complete the firing sequence; and in response to a catastrophic failure which renders the firing drivetrain inoperable, to activate a bailout mode in which the processor disables the electric motor . a processor ; and a memory storing program instructions; characterized in that the program instructions, which when executed by the processor, cause the processor to operate as follows: in response to an acute failure which causes the firing drivetrain to operate at less than optimal performance levels, to activate a safe mode in which the processor modulates the mechanical output of the electric motor to limit the speed of the firing drivetrain and allow the electric motor to complete the firing sequence; and in response to a catastrophic failure which renders the firing drivetrain inoperable, to activate a bailout mode in which the processor disables the electric motor . in response to an acute failure which causes the firing drivetrain to operate at less than optimal performance levels, to activate a safe mode in which the processor modulates the mechanical output of the electric motor to limit the speed of the firing drivetrain and allow the electric motor to complete the firing sequence; and in response to a catastrophic failure which renders the firing drivetrain inoperable, to activate a bailout mode in which the processor disables the electric motor . <EOS>