Toshiba satellite turned off and on with black screen

My Toshiba satalite laptop just turned itself off and keeps turning on and off with no screen. Just cap lock an number lock luminaries along with power button.

I’ve tried  removing the battery and running on mains only no changes.

tried power button 60 sec then FN F5 Power together for 60 sec etc

also F8 and power but nothing seems to work.

any help would be greatly appreciated