" something is rattling inside ... "
Do you mean you can hear something moving when you move it (loose bits banging around), even when not plugged in?
Or, that you hear loud mechanical noises when you try to boot up?
Either way - you need to open it up, and look around inside. You may just have a connection that has come loose inside, which could mean that the hard drive is not connected. That will be a good reason why you see the flashing "?".
But, you do need to discover what is loose, or causing that noise (which could just be some little piece is jammed into the fan blades, causing noise when the fan turns. You have to actually look at the fans to make sure. And, you have to open it up.
Do it yourself. Or, if you are not comfortable with opening up the case, take it to an Apple store, or an Apple-authorized service shop.
and, yes, I also hope that you do have a backup of your drive. This would likely be one of those times that you will need that backup.