SIRIS, ALTO, and NAS: Reset CMOS on a Datto S3X, ALTO 2 or ALTO 3 that won't boot and displays a red light




Your Datto S3X, ALTO2, or ALTO 3 is unable to boot and is displaying a red error light.


  • Datto SIRIS 3 X1
  • Datto SIRIS 3 X2
  • Datto SIRIS 3 X4
  • Datto ALTO 2
  • Datto ALTO 3


You can often resolve this issue by resetting the CMOS on the Datto device.

Although you can access the CMOS reset button through a hole in the baseplate, Datto recommends removing the baseplate first to avoid accidentally damaging the motherboard.

1. Unplug the device

2. Twist the four rubber feet with your fingers to remove them.

fig1.pngFigure 1: Bottom of the device (click to enlarge)

3. Remove the baseplate.

4. Press the CMOS reset button (circled in red below).

fig2.pngFigure 2: CMOS reset button (click to enlarge)

5. Put the baseplate back on and screw the feet back in.

6. Plug in the device and turn on the power.

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