I have a late 2015 27” iMac with 1TB Fusion Drive. Normally I was using my macOS through an SSD connected to the USB and I was sooo happy about the performance of my computer. One day it restarted itself while in sleep mode and… never be able to start again;
Symptoms:
Apple logo appears when I connect my iOS containing external SSD, but the progress bar never fills up (it stays blank forever)
Question mark appears when I do not connect my external SSD with iOS.
Command+R does not work and OPT+Command+R do not continue after some point during start up
Apple diagnostics say my computer is ok
I resetted my NVRAM and tried all possible startup key combinations including Command+S (I cannot reach to Terminal (some weird data log appears and no place to write a command)
Apple authorized service cannot do anything since my computer is considered as vintage
I talked to the apple expert, and he said most probably my HDD is dead (it is silent now and I do not hear it anymore).
Do above symptoms root from the dead HDD?, even all my iOS data is in my external SSD?
Will replacing my internal HDD to a new internal SSD solve the problem?
I cannot split my Fusion Drive since I cannot reach to the Terminal app, will that be a problem?
What symptoms do you think I will have right after replacing my HDD with a new Sata3 SSD?
I like my computer and want it back, thanks to all in advance