Chosen Solution
After installing the upgrade the mac is just generating a tone every 4-5 second and does not boot. I saw on the guide page that at least 2 other users had the same problem. Anybody has an idea of what to do? Thanks Frederic Update (09/25/2018) I am running high sierra on that mac but, with only 2GB, it is struggling, hence the temptative upgrade…
Do you still have the original RAM (in working order)? If so, try plugging the original RAM in and see if this behavior continues. A beep every 5 seconds typically means bad, incorrect or no RAM.
In order to run 16 GB you’ll need to be running OS-X Lion 10.7.5 or higher and make sure you’ve updated with the latest EFI firmware. The highest this system will run is macOS High Sierra 10.13.6 If you’ve not updated to El Capitan OS-X 10.11.x or newer you’ll either need to do that first or manually install the newer EFI firmware from here: About EFI and SMC firmware updates for Intel-based Mac computers
