No Entry Sign Mac

Model a1502 2 4 2 6 or 2 8 ghz dual core intel processor released october 2013.
No entry sign mac. I have a no entry sign on my imac when i start it up answered by a verified mac support specialist we use cookies to give you the best possible experience on our website. By continuing to use this site you consent to the use of cookies on your device as described in our cookie policy unless you have disabled them. Enter the firmware password to continue. If your mac is using a firmware password the lock icon appears when you try to start up from another disk or volume such as an external drive or macos recovery.
When starting your mac if you run into a prohibitory sign and the system will not boot there are a couple of things you can try to address the problem. Enter the four digit or six digit passcode. But i keep seeing the no entry icon. Seeing a no entry sign after a new crucial m500 installation i just installed a new crucial m500 drive into my 2009 2 0 ghz mac mini.
Managing a prohibitory sign at os x bootup. Macbook pro 13 retina display late 2013.