The real-time clock on the SM2 series recorders is powered by two AA batteries. When those batteries die, everything aside from the schedule and the clock can continue functioning properly, so it can be difficult to spot the problem.
We recommend replacing both AA batteries annually. To do so, gently insert a credit card in between the Velcro fasteners on the right side of the AA battery harness to loosen the hold. You can also use a screwdriver to gently lever the harness out of the recorder. Do not try to force the AA battery harness away from the Velcro, as this could tear away the wires connecting the battery harness to the rest of the electronics.
With no microphones plugged into your SM2, turn the unit on, then press UP and DOWN simultaneously to start an instant recording. If your recorder's screen displays "Preparing to record" and does not actually begin recording, then your clock batteries are either dead or disconnected from the SM2's electronics.
If you encounter this issue or other erratic behavior, even after replacing both AA batteries with brand new alkaline cells, please contact Wildlife Acoustics support.