My daughters sonicare toothbrush makes a noise but the bristles do not vibrate anymore. She only used it for about 4 days.

There is probably no fix for it, as it is not made to be repaired; if it malfunctions, you are supposed to discard it and get a new one.
However, it is likely the problem is in the switch of the toothbrush.
It may have some foreign matter inside that is causing the contacts to close when not in use, and that its why it is turning on all by itself. If you want to try something to fix it, I would get a tank of compressed air and a blower and try blowing the air into and around the off/on switch.
It might fix it, or it might destroy it.

Hi Noel:
The instructions that came with it should tell you.
I'd guess at 2 possibilities:
1) Needs re-charging
2) Brush needs replacing

Are you sure the brush attachment is "tight" to the handle? Do you have a new brush to try? It should confirm handle is bad or it is the brush attachment "tightness" .

maybe the battery

The best electric toothbrushes are the Oral-b Professional Care and the Phillip Sonicare Diamond Clean. You can find more information on these electric toothbrushes on their respected websites: http://www.usa.philips.com/c/diamondclean/289711/cat/en/ and http://www.oralb.com/products/professional-care-smart-series-4000/.

This happened to me as well. One long, two short beeps. Incessantly. Only happens when brush is on the charger.

Try this simple fix first. Hold down the SILVER button for 5 seconds while the toothbrush is on the charging base. If the fix works, it will fix the problem immediately like magic.

If that doesn't work, try this:
1) remove brushhead.
2) use screwdriver in the base and turn 1/4 turn
3) push out assembly from the top
4) dry the inside of of the base handle. allow to air dry
5) allow the switch to air dry
6) reassemble

The best tutorial for repairing Sonicare toothbrushes is here:
Repairing your Sonicare
The problem is either a corroded circuit board or worn-out Ni-Cad batteries. Both repair solutions require soldering, but full repair is possible.

I had mine for many, many years without a problem. I bought mine directly from them when they were first starting up, before they started advertising.
There's no easy fix as the internal electronics have gone kapute. Before pitching the unit for a new one, contact Sonicare and see if they will be willing to work with you by replacing it for a discount.

If not, the Oral-B is FAR superior product and is the only type I see recommended by dentists. Really made a difference over the Sonicare.

Both are highly rated however. Ask your dentist for his opinion.

2018 reiview:
Best Electric Toothbrush Reviews of 2018 Reviews com