Epson TM-C3500 Series Technical Reference Manual page 71

To switch the power switch by inserting a long, thin object into a hole
Attach the power switch cover after punching the hole in it.
The hole cannot be punched in the power switch cover after it is attached to the printer.
1
Punch a hole in the power switch cover by pushing the middle of it with
a hard, fine-tipped object.
2
Push the power switch cover onto the power switch of the printer.
Chapter 2 Setup
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