HP CP1700

Hello when i turn on my HP CP1700 it asks for letter paper (A4 Paper has
been loaded) then it asks for A4 Paper (in the tray or manual) despite
feeding paper it just goes though the printer and does not print! (This is
the inbulit self test, i have not even got as far as windows) It just chucks
out paper then asks for more to be loaded (Sometimes A4 sometimes Letter)