Brother DCP-J552DW Service Manual page 213

If the firmware write mode does not start automatically, run it to write the firmware with the .upd
extension by following the steps below.
1) While holding down the power switch, plug the power cord into an electrical outlet. When
the [Home] key lights, release the power switch and immediately press the power switch
once to display the following pattern.
2) Within three seconds after the above pattern appears, hold down the power switch for
approximately two seconds to display the following pattern.
3) Within three seconds after the above pattern appears, press the power switch once to
display the following pattern.
4) Within three seconds after the above pattern appears, press the power switch twice to
display the following pattern.
5) Within three seconds after the above pattern appears, press the power switch 3 times to
display the following pattern.
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