Epson EPL-N2750 Quick Reference Manual page 27

The program ROM cannot be written to. It is also
possible that writing to the ROM was not completed.
To correct this error, do one of the following: 1) turn off
the printer, then turn it on again, 2) press the Continue
button, or 3) reset the printer by pressing the ALT and
Reset buttons at the same time.
The printer is writing data into the ROM module in slot
A.
The printer is writing data onto the program ROM.
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