HPS script issue [SOLVED]

[Devil Dogs SF]

I'm still doing something wrong here, don't exactly know what. I probably messed it up in this failed fix I just tried, I still don't understand scripting at all:

void OnStart(AddUseItemCallback("", "key_tomb_rusty_1", "metal_1", "KeyOnDoor1", true); )
{

void KeyOnDoor1(string &in asItem, string &in asEntity)
{
SetSwingDoorLocked("metal_1", false, true);
PlaySoundAtEntity("", "unlock_door.snt", "metal_1", 0.0f, true);
RemoveItem("key_tomb_rusty_1");
}

void OnStart(AddUseItemCallback("", "key_torture_chamber_1", "prison_1", "KeyOnDoor2", true); )
{

}

void KeyOnDoor2(string &in asItem, string &in asEntity)
{
SetSwingDoorLocked("prison_1", false, true);
PlaySoundAtEntity("", "unlock_door.snt", "prison_1", 0.0f, true);
RemoveItem("key_torture_chamber_1");
}

void OnStart(AddUseItemCallback("", "key_tower_1", "hatch_ceiling_1", "KeyOnDoor3", true); )
{


void KeyOnDoor3(string &in asItem, string &in asEntity)
{
SetSwingDoorLocked("hatch_ceiling_1", false, true);
PlaySoundAtEntity("", "unlock_door.snt", "hatch_ceiling_1", 0.0f, true);
RemoveItem("key_tower_1");
}

Sorry if this is something super simple, but I am thoroughly confused...