Yeah, this one's common. It's almost always the auto-shutoff getting triggered early because it thinks the carafe isn't in place.
- Make sure the glass carafe is sitting perfectly flat and centered on the warming plate. Give it a little wiggle to seat it.
- Check the little metal tab on the underside of the warming plate. If it's stuck down or bent, it won't sense the carafe's weight. Try prying it up gently with a flathead screwdriver.
If that didn't work, the thermal sensor might be faulty. That's a more serious internal issue.
Heads up: The brewer is designed to shut off automatically two hours after the brew cycle ends if the carafe is left on the warmer. That's normal, but your issue is happening way before that.