An apparatus includes a body, a shaft, a stapling head assembly, and an anvil. The body includes a motor, a first user input feature, and a second user input feature. The first user input feature is operable to activate the motor. The shaft extends distally from the body. The stapling head assembly is positioned at a distal end of the shaft. The stapling head assembly includes an anvil coupling feature, at least one annular array of staples, and a staple driver. The second user input feature is operable to drive the anvil coupling feature longitudinally. The staple driver is operable to drive the at least one annular array of staples. The motor is operable to drive the staple driver. The anvil is configured to couple with the anvil coupling feature. The anvil is further configured to deform the staples driven by the staple driver.