Buttons not working batteries

Did you check if the batteries are inserted correct? + to + and - to -
Also it could be you have the wrong batteries.
Depending of what you use, always be sure all batteries are the same, charged and suited for your camera. Most of the time even new Ni-CD rechargeable batteries won't work, because the voltage is to low, according to Ni-MH or alkaline batteries. Checking the voltage of every cell with a multimeter could tell you for sure the batteries are good. Voltage should be jus above the voltage printed on the battery when measured.
Never use manganese (Zinc-Carbon) batteries, because they don't have enough capacity to let a camera work correct.

The warranty should be at least one year.
Try a warranty repair or replacement.

Brand new as in you just opened it out of the box? If thats the case you have to charge the re-chargeable battery first, then put it in the camera and it should work fine. Try giving the battery a charge first if you haven't already.

what brand and model of camera?

this is not malfunction.
According to its manual, just turn it off ,wait for one minute and
turn it on again. It'll reset th camera. You need to reset the date/time.

Sounds like a defective thermostat!

Clean the battery holder with a pencil eraser, otherwise go for good brand rechargeable battery AA 2700 mAh try it.

After i replace standard alkalines with rechargeable NiMH batteries Sony 2700 Ni-MH or Varta 2700 Ni-MH it's was working!
My camera it's working now!

Turns out the brand new batteries I installed were dead.