@RBWilliams glad I could help.
To turn on the Camera you have to press and hold the power button. To turn it off you have to use something like a paperclip to press the reset button behind the small hole (see the picture at https://docs.m5stack.com/#/en/unit/timercam_x). There it's also documented how to turn it on and off:
The low-power power management solution adopted by the Timer Camera series is different from the CORE and StickC devices. When in use, the PWR button is used as a power-on button(long press 2s). If you need to shut down the device, you need to use the software API or press the Reset button on the PCB.