Brother TD-2120N - Manual (Page 84)

Updating P-touch Editor (all models) / Updating the Firmware (TD-2020/2120N/2130N only)
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9
d
Select the [Printer], ensure that [The machine is connected correctly.] is displayed, and then click
[OK].
e Select the [Language], select the check box next to the firmware to be updated, and then click
[Transfer].
Do not turn off the printer or disconnect the cable while the data is being transferred.