Is there anything stuck in the disk drive? That can cause some very weird noises. Other than that could be the fan with an obstruction in it. Might have to crack this sucker open to see what’s up.
That’s the best option really can’t find out anything with the bastard closed it sounds like a moving part but they are all at the front though fan noise escapes through the back
Pull the hard drive out then power her back on and see if it’s stopped the power supply can’t click i’ve had two separate models apart and they are all solid parts inside