Brother HL 5370DW - Manual (Page 138)

Troubleshooting
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7
f Put the drum unit and toner cartridge assembly back in the printer (press firmly).
g
Fully close the front and back covers.
h Pull the duplex tray completely out of the printer.
i Pull the jammed paper out of the printer or the duplex tray.
j Put the duplex tray back in the printer.
k
Make sure that the Back Cover and Paper LED are off and then, the Status LED lights green.