The blinking icon on the screen means the mac is having a hard time finding system data to boot off of. So yes, it can’t see/read the drive.
This is a 2004 iMac, the lampshade one? It shouldn’t be too difficult. Easier than popping open one of the newer single panel machines. Here’s a video describing the whole process (I didn’t sit through it, so…)
//youtu.be/3Z_HNvjLe-k
Also, a guide
(If you hadn’t found them)
Be aware that the freezer trick is something to do as a “I hope I can get my data off of this drive before It completely dies” solution. This is not something that will magically fix the drive and let you keep running. You should get/borrow an external disc case, freeze the disc, and then copy the contents to another disc as the first thing you do. Treat the disc like nitro glycerine - could blow at any moment.
My suggestions for this kind of thing:
- Be Patient
- Ground Yourself (An anti-static wriststrap is best, but really just touching some metal should statically discharge you. Don’t go scooting your feet around on carpet while you’re doing this)
- Make sure you have all the tools before hand
- Have a replacement drive (so you don’t have to open the machine twice)