I had to dash away to collect my daughter: I should have added that the only way to turn it off is to unplug it. When I plug it in again its still effectively switched on so I get the chimes etc., etc. iMac about four years old running Mountain Lion.
I.E. restart your Mac while pressing the Shift key at the same time, after you hear the startup tone release the Shift key as soon as the Apple logo appears.
Safe Boot appears on the Mac OS X startup screen.
Shut down your computer.
Restart your computer again as normal.
During this procedure black lines will appear on your screen, this is normal.
No joy: Method 1 ; same result but with the addition of a progress bar below the apple and the spinning thing. Unfortunately I looked away before I could see if the progress bar attained its full length before the screen blanked again.
Method 2 : Gave me the apple and the spinner and then a bright blue screen with vertical black lines, with must have unnerved me as I let go of the keys! Then nothing. Unplugged again.
Method 2, second attempt, wouldn't give me the chimes until I pressed the 'on' button, keeping my fingers on the 'Command and R' keys, same result but with a pale bluey/grey screen with vertical lines, I noticed that the mouse light was on, when my fingers began to ache I let go and went for a cup of tea. After ten minutes just the bluey/grey screen, and I noticed that the mouse light had gone out. Unplugged it. Going to bed soon!
If you can't get even the recovery partition to work (to run Disk Utility as Drew suggests, do you have a clone you could try starting from? (It doesn't sound good for your hard disc)
Alternatively, see if there's anything helpful here:
Lifewire — started up with command & s held — screen full of text with, off to the right; 1 *** Launchd (1) has started up in single user mode ***, 1 *** Verbose boot, will log to /dev/console. ***, 1 *** shutdown logging is enabled. ***
At the bottom left of the screen it said — If you wish to boot the system:
exit
:/ root# --fsck, but all I can get then is 'command not found'
Also LifeWire — started up holding Command + Alt + P + R —
chimes repeated every 10 seconds ad infinitum so I let go and after a few seconds was presented with half a dozen choices of start up partition — chose Recovery 10.8.5 and got back to the lovely dark blue screen. If nothing happens in ten minutes I'll try again and choose a different partition.
Just to cover off all the bases, could be hardware:
Depending on the age of your Mac, you may have an Apple Hardware Diagnostics CD in your original discs. Try booting from that and running the hardware tests (choose the quick version/not the extended test for now).
For a newer Mac, press power and then immediately press 'D' on the keyboard.
More info, including more desperate options like network start-up, is here and here.
Tried again, letting go after the third chimes and got nothing but a white screen.
Tried again, letting go after ten chimes. Apple & rotating thing — white screen — went to bed.
Morning Tony, Power and D did nothing — Power, Option D did attempt to do something but I ended up with a picture of the Earth with a warning sign on it,and under that it says, 'apple.com/support .501 0D'
This is really weird; I post something on here, and when I come back in a while your post, Tony, has appeared above mine, and allegedly posted before mine!
Chimes: one long chime, which is normal, but repeated at about ten second intervals.
My best guess is that this is hardware related. The most likely issue is the hard drive but it could be a video card or something more. Can the people you bought it from check that for you? Are they an authorised Apple reseller? I don't think there's an Apple Store anywhere near you.
Hi Eric, can you find someone locally who can install an appropriate 'clean' macOS on an external drive and then use that to see if your internal drive is faulty? Just a thought.
I'm trying to get this post to appear before all of the others now (but I'm not optimistic).
You say "one long chime, which is normal, but repeated at about ten second intervals", Apple says "One tone, repeating every five seconds". It would be wise to check the frequency of your chimes.
If you are getting the 5 second chime, that indicates a RAM problem. Have you added or changed any RAM recently?
If it's easy (I don't know what type of Mac we're talking about), you could try reseating the RAM modules anyway: turn off the power, then remove and reinsert the modules. Earth yourself just before you do it (touch a tap or central heating radiator or whatever and don't wear your '80s nylon tracksuit) and handle the modules by their edges - DON'T touch the gold connector pads.