Its the padlock with a window underneath for a code
I tried that first, didn't work
I already answered that
Yes I'm here
It makes no difference how long I hold it, I still get the padlock back
Yes, it does shutdown
No, I disconnected it when the problem started
Its the latest OS, Yosemite
That is what I have been doing. All It comes up with is the padlock screen
Yes, even If I restart & do nothing
I bought it secondhand but I have had it for over 4 years with no problems
No I don't
It's a 27" iMac, It is probably 5-6 years old & it's the top of the range one at the time. I can't get any more information as it needs to be running for that.
Choose Apple menu > Shut Down.
Locate the following keys on the keyboard: Option, Command (⌘), P, and R. You will need to hold these keys down simultaneously in step 4.
Turn on your Mac.
Immediately press and hold the Option-Command-P-R keys. You must press this key combination before the gray screen appears.
Continue holding the keys down until your Mac restarts, and you hear the startup sound for the Fourth time.
Release the keys.
Have just done that twice more & still only getting the padlock screen
I don't have any other suitable memory for this machine. I have held on to the keys for ages but there is only 1 reset chime.
Can you erase the drive or do you need to try and save what is on it?
I have just removed & replaced the ram to clear it, I will go & try the T key now
The T key still resulted in the padlock screen, not had the firewire symbol.