You open the file in setup(), read everything in the file and print it to the serial port. Then, you close the file.
Then, in loop(), you try to read from a file that is not opened. How can you expect that to work?
You open the file in setup(), read everything in the file and print it to the serial port. Then, you close the file.
Then, in loop(), you try to read from a file that is not opened. How can you expect that to work?