Brother MFC Series Service Manual page 204

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