Genesis 2:16 And the LORD God commanded the man, “You are free to eat from any tree in the garden; 17 but you must not eat from the tree of the knowledge of good and evil,
for when you eat from it you will certainly die.”
Genesis 3: 4 “
You will not certainly die,” the serpent said to the woman. 5 “
For God knows that when you eat from it your eyes will be opened, and
you will be like God, knowing good and evil.”
6 When the woman saw that the fruit of the tree was good for food and pleasing to the eye, and also desirable for gaining wisdom, she took some and ate it. She also gave some to her husband, who was with her, and he ate it. 7
Then the eyes of both of them were opened, and they realized they were naked; so they sewed fig leaves together and made coverings for themselves.
22 And the LORD God said, “
The man has now become like one of us, knowing good and evil.
He must not be allowed to reach out his hand and
take also from the tree of life and eat, and live forever.”
Now it seems to me that things happened exactly as the serpent said, and also the serpent told them more than God did concerning the tree. Both God and the serpent didn't tell the whole truth though. As for metaphorical death, I don't think there was any indication when God gave the command that the death would be metaphorical.
Also consider these:
29 Then God said, “I give you
every seed-bearing plant on the face of the whole earth and every tree that has fruit with seed in it. They will be yours for food.
In the
middle of the garden were the
tree of life and the tree of the knowledge of good and evil.
2 The woman said to the serpent, “We may eat fruit from the trees in the garden, 3 but God did say, ‘You must not eat fruit from the tree that is in the
middle of the garden, and you must not touch it, or you will die.’”
Here, already God goes back on His word (if you interpret Genesis literally). Furthermore, Eve either didn't know God's command, or God changed His command, and now Eve also think God commanded her not to eat from the tree of life?