Epson TM-U200D series Operator's Manual page 36

If the printer stops working and the ERROR light is blinking, turn
the printer off, check for jammed paper, and remove it by following
the instructions on page 3-3, if necessary. Then turn the printer
back on. If the printer still does not work, unplug the power supply
cord from the outlet immediately; then contact a qualified service
person.
CAUTION:
The print head becomes very hot during printing. Allow it to
cool before you reach into the printer.
Note:
The power switch and PAPER FEED button can also be used to
start the self test.
Using the Printer 2-3