Starts up, red striping, goes to blue screen, does not boot

Hello

When turning on my desk top first red lines vertical and black lines horizontal come up on the screen. Second the Apple icon shows up in what seems to be in the back ground. Third the rotating black dashed indicator shows in the back ground. Forth a blank blue screen comes up. Sometimes the blank blue screen turns into uneven dashed lines. It never finishes booting up making programs accessible. I can run the hardware diagnostic with the text barely readable in the back ground and it indicates that the there are no Hardware issues. Thanks in advance for any help.