EPSON printer WF-3640 touch screen is unreponsive & won't power down

EPSON printer WF-3640 touch screen is unreponsive & won't power down

EPSON printer WF-3640 touch screen is unreponsive & won't power down... I've tried holding down the power button, as well as power + STOP button, and cannot turn it off. Right before this happened, I had cleaned the print heads to fix printing issues.