Hi there
My imac won't start .... 8 got some vertical bars 9n the screen... won't go past that
Question marked as
That sounds like a GPU failure. Try restarting in Safe Mode per Use Safe Mode to isolate issues with your Mac and then restart normally. If the problem continues, please take it to your local Apple Authorized Service Provider to be professionally diagnosed.
Also, when posting please let us know the model year and version of Mac OS installed.