Unable to log onto desktop..

I have a Macbook Pro 15" (Late 2012) Unibody with High Sierra installed.

Recently I have not been able to get onto my desktop either by entering password or by using the Recovery.

I power on the Macbook and the Chime goes...the my Logon icon appears but the screen has hundreds of horizontal red lines showing.

I enter my password and it starts the loading...The progress bar gets to 3/4 of the way across and the screen just goes white.

On other occasions, after entering password the screen goes white and then powers off after 3mins.

I have tried the recovery mode; I get the spinning globe and the progress bar but about 3/4 across the Macbook restarts.

I have tried resetting the NVRAM and have done an SMC reset. Any help would be great.