My car will not start and when I do turn the key forward to a certain point the 5 pin main relay starts clicking rapidly and the automatic transmission shift lever solenoid goes crazy with the plunger going in/out rapidly also the dash lights start flickering. There isn't any power to anything else and when I tried turning the headlights on it start making a weird buzzing noise without the lights coming on. So far I've replaced the main relays and ignition switch with no results.
Have you checked the battery? properly charged and the connections and terminals? I would start there.
Then, check all the earths or grounds between engine / body, engine / battery and body / battery as the next step. Then you are probably into looking at the feeds from the battery to the major components and controls.