Nikon D40 won't turn on?

Had my d40 since 2008, its been good, few problems
and the other day i had it plugged into the computer (my mac) to download pictures.
It then turned off and I figured it was because the battery was low, so it mustve died. Plugged in the battery. It charged for a couple hours (light was flashing etc.) and put it in the camera. And it won't turn on Help!

And there's the reason why I use a card reader.

Most likely the battery is at fault, eliminate that by trying another fully charged battery

Camera battery is used when transferring pictures from camera to computer. Use a USB card reader. It's simpler.

Fully charge the camera battery before unplugging the charger. You can leave it overnight for maximum charge.

The memory card should be detected without problems by your Mac. If not, there's a problem with your memory card. Replace it.

If after fully charging the battery, the camera still does not go on, bring it back to the store you bought it from for servicing.