Epson CX6500 Reference Manual page 285

When you scan a thick or large document, you can remove the document cover.
Note:
When you place a document without the document cover, make sure you press the
document from above to keep it flat.
When you press the document, do not move the document and do not add too much
pressure.
Removing and installing the document cover
When removing the document cover, open the cover, then pull it up.
When installing the document cover, install it in the reverse order of removing it.
Caution: