Help needed - Yaris Not starting

[Abk911]

I have a 2008 yaris sedan (80k miles) Base model.

I drive the car everyday and it ran just fine (regularly services ni lights to date). Today morning (4 am) tried to start the car and it wont. When i rotate the ignition key i hear noise of moving parts (metals) under hood but engine does not kick in. The metal moving noise happens each time i turn the ignition. This is not the noise of an engine firing up its like metal parts moving in engine noise like its cranking but its just the engine parts moving (for a second i thought everything in the hood is broken. My battery is 4.5 years old but every thing in car - lights, power windows, vipers, radio etc are all working. also of what i recall when battery is weak or dead the ignition usually simply gives up and there is no engine parts noise - at least that happened to my other cars? correct me if i am wrong. Now since the car does not start the "oil pressure" light is on (not sure if its supposed to be on when the ignition key turned one notch? (all other lights go away in 2 odd seconds but this one remains and flickers when i try to start the car. (I clearly remember that the oil pressure light was NOT ON yesterday and so does my wife. Yaris dashboard is very simple (2008) to have missed a oil pressure light - also oil was changed 2k miles ago. I am on a business trip and first thing i will do when I headback is change battery and try and or use jumper cable. I am although worried cause each time my wife tries to hit the ignition key all we hear is metal moving in the hood and no start up etc. This noise is scaring me and i hope the damage is not much worse. Anyone who can guide will be much appreciated?