iMac rebooting and rebooting

I need some help understanding what’s going on with my old iMac mid 2011 that cycles through rebooting and the grey screen, going black, and rebooting again endlessly? It has an SSD that I swapped out few years back, but if possible, would like to make it useable. Any ideas??

Thank, I tried booting into safe mode, got the apple logo and chose an external drive to Boot up, but again, a grey screen. Is this the graphics card that’s blown??

Its a 21.5“ mid 2011 Imac and its not integrated
I was thinking to take it apart and replace the Graphics card, but it looks too difficult