Fan or Hard Drive Failure
Thanks for the help with your sharing.
My iMac has been running for about 10 years and got shutdown really, really, really seldom.
As other people posted here, it doesn't boot anymore (loading bar stops, and then it reboots) and the Diagnosis Tool shows that :
I've understood that this is about the HDD or its fan.
Well, I opened my iMac and discovered there's is no HDD, nor its fan anymore.
Indeed, quite a few years back, I've asked an Apple Reseller to replace the hard drive with an SSD, and so he did, taping the SSD below the Optical Drive.
Could you people help me understand how I might repair this ? Shall I conclude that it is a logic board error ? Thanks to all for your inputs.