Sorry for the ludicrously specific question, but I just cannot work it out!
Mostly when I turn on my rear Raleigh RX10 USB rechargeable rear light it has a constant beam. Pressing the power button again toggles the intensity of the light. Pressing and holding the power button turns the light off (or back on). Occasionally it comes on flashing instead of constant, but I have no idea how. How can I reliably and predictably turn on flashing mode?