Why will my DC35 not turn on

Here are a few suggestions for troubleshooting:

- Check that the battery is fully charged. Try charging it for several hours and then trying again. Some batteries need an initial long charge before they will hold a full charge.

- Make sure the battery is installed correctly and securely in place. It's possible it is loose or not making proper contact. Remove and reinsert the battery to ensure a good connection.

- Inspect the power button and switch. Make sure they are clean and not obstructed or damaged. The button may need to be pressed firmly and securely.

- Check for any blown fuses in the vacuum, especially if you see the power light come on briefly. There may be a faulty connection. Replacing fuses could help.

- Try resetting the vacuum by leaving the battery unplugged for a few minutes before reconnecting it. Sometimes this resets components.

- Open up the vacuum and inspect the internal wiring connections. Ensure all wires are securely plugged into the appropriate ports. Reconnect any loose wires.

- If you have tested all of the above, it's possible there is an internal electrical issue with the motor or wiring. At that point, repair may be difficult for a non-technical person. An appliance repair shop may be able to diagnose and fix the problem if it's electrical in nature.

I would try all the basic troubleshooting steps first before assuming the vacuum needs professional repair. But if you've tested everything and it still won't turn on, it likely will need servicing by a qualified repair shop.