Here's the owners manual Panasonic VIERA Plasma Users Manual looking on page 18 this is what it has for this condition:

"The TV has gone into shutdown mode to protect itself. Try unplugging it for a few minutes and connecting it again. If there was a temporary power surge on the AC line it may now be OK. If the blinking returns, call 1-877-95-VIERA (U.S.A.) or 1-866-330-0014 (Canada)"