If your Onefinity CNC BB Buildbotics Controller will not power on:
WARNING: ALWAYS DISCONNECT YOUR ONEFINITY CONTROLLER FROM IT’S POWER CABLE BEFORE OPENING
- Before doing anything else, ensure the estop is fully depressed. It takes a twist and a very hard pull to get it fully disengaged. Don’t worry about damaging it, since the controller already doesn’t turn on. Many have mistaken that they disengaged the estop. Disengage and engage it (with the machine unpowered) a few times until you can ‘feel’ the engaged vs disengaged and ensure it’s disengaged.
- Make sure that the inside of your controller is free of dust and debris. It is normal to accumulate a small amount of dust in the controller because of the nature of the machine and its use, but a large amount of dust build up may cause your controller to fail. It is good practice to remove dust from your controller periodically with compressed air and a soft bristled brush. WARNING: DO NOT VACUUM THE CONTROLLER OUT AS IT CAN SHOCK THE BOARD AND KILL THE CONTROLLER
- Open the controller by removing the 4 bolts on the BACK plate of the controller.
- When powering on:
On the big silver box inside (the power supply) there is a tiny led near where all the power wires connect on the left side (looking from the back of the controller). with the controller connected back to wall power:
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Does the green led light on the silver power supply light up with the estop pushed in/pressed? (YES OR NO)
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Does the green led light on the silver power supply light up with the estop fully released/twisted and pulled up? (YES OR NO)
If the answer to #2 is no (the green light doesn’t light up), the controller board is dead and a replacement controller will need to be purchased.
Please see #10 for a link to the replacement controller
- NOTE: 2020 CONTROLLERS MAY NOT HAVE THIS SPECIFIC FUSE. Disregard this section of your controller does not have this fuse. Open the controller from the back and check that the inline fuse is intact (in the black casing on the back of the board). DO NOT open the power supply (silver box).
- It’s possible that a cord came loose inside the controller. with the controller unplugged, remove the back plate and check for any loose or disconnected wires, focus on this cord in particular (THIS WIRE PROVIDES POWER TO THE CONTROL BOARD)
Videos
Rocker Style(vhttps://www.youtube.com/watch?v=lpl2sWEzMKs)
Push Button (https://www.youtube.com/watch?v=N7mb4dWTFM4)
- Your controller might have a bad power switch. You can test the power switches connection by completing the circuit. With the controller flipped to the “on” position, touch both wires attached to the switch simultaneously(this is low voltage you will not feel). Does the fan kick on? Is the controller running while your finger completes the circuit?
Rocker Style:
The below pictures show how to bypass the power switch without your finger. Remove the two red plugs on the back side of the power switch terminals and slide them together. Sometimes a finger isn’t conductive enough.
Replacement here: https://www.onefinitycnc.com/product-page/on-off-switch-rocker-style-switch-controllers-only-bb-controllers-only
Correct Estop wiring Digaram:
Push Button Style:
The picture below shows how to bypass the power switch on a push button controller version. Connect a short wire to both outside pins (ignore the inner pins indicated with a red x) together to complete the circuit.
Replacement here: https://www.onefinitycnc.com/product-page/on-off-push-button-switch-bb-controllers-only
ETOP
- It’s possible to have a bad estop. If the last thing you’ve done was press the estop before the controller didn’t boot, lets try bypassing it. Use a phillips head to loosen the silver screws and remove the red wires going into the estop. Then, twist the 3 wires from one side together with the 3 red wires from the other. Use electrical tape or a cap to cover them. Once finished, reconnect power and try booting up. If it boots up (which would confirm an estop issue) try using compressed air to clean out the estop from debris.
You can purchase a replacement Estop https://www.onefinitycnc.com/product-page/emergency-stop-switch-bb-controllers-only
SD FLASH
- If you have checked and ensured that the cables are all connected correctly and the controller still won’t turn on, we’ll try recovering the SD Card image by following this link: How to reflash the operating system on the Onefinity (Full SD card image)
Purchase Replacement
- If none of the above steps work,
A replacement controller can be purchased here:
We do not offer a repair service. A replacement controller is the only fix for a ‘dead’ controller.
The BB Buildbotics Controller was discontinued in 11/2025.
You can upgrade from your bb buildbotics controller to the new Redline controller through the IPP program here: