One day i took my is300 262k miles (swapped engine and trans from a gs300 says past owner no proof) on a cruise and came back home and let it sit for a few hours and tried to start it and it would only crank but not start, everything was working at this point, dash lights and all and the fuel pump would make its hum, so i took a look under my hood and found that my fuel pump relay the outer casing was cracked so i ordered another one and it hasn't arrived yet (well get to that later) and i also got new terminals (battery started dying so i disconnected it to charge it) and the terminals were basically done and so i charged the battery and went back at it another day and reconnected the battery and now i have no dash lights and most of the electronics dont work, basically the only things that work are the hazard lights the interior light and the door lights nothing else works but it cranks, fuel gauge doesnt move nothing im very stamped at this point thinking i wasted 2 grand on this car please help ive also found that the 120a alternator amp was blown and im not sure if this is supposed to happen but when i took the fuse out the prongs stayed in the fusebox and the replacement fuses i found have prongs in the fuse so im very confused by what happened there, please help im new to the is300
forgot to mention im currently using the old cracked fuel pump relay i was talking about but worked fine before and all the wires and such inside the relay look fine

 

If your battery connections are all on. Then It may be the ignition switch. Not the cylinder, the electrical contact part.