Panasonic Plasma TH-42PZ77U Power Light Fla...

The power supply board seems to have died. If its under warranty, check with Panasonic. If not, whats your nearest electronics repair shop? Just make sure they dont charge you an arm and a leg.

This is a major failure. This kind of thing is why you should always keep these TV's under warranty. Now you need to download the service manual, verify what the 7 blink code means and start replacing expensive boards. I believe on this unit one of the power voltages is wrong and you'll need the SC, SU, and SD boards.

1 Blink SOS: This shutdown operation is usually caused by a lack of communication between the A and the D boards.
1 Blink SOS: This shutdown operation may be caused by the improper connection of a SS board connector to the panel.
2 Blinks SOS: Pin 87 of the MPU IC9003 monitors the 15V line. During normal operation, the transistors Q9053 and Q9054 output a high to pin 87. If the 15V line is missing or shorted, a low is provided to pin 87. As a result, the unit shuts down and the power LED blinks 2 times.
3 Blinks SOS: IC9807 is a 3.3V regulator located on the D board. Its output is monitored by IC9003. If the 3.3V is not present at pin 86, the MPU shuts down the unit. The power LED blinks 3 times.
5 Blinks SOS: Pin 85 of the MPU IC9003 monitors the 5V line. During normal operation, the transistors Q9051 and Q9052 output a high to pin 85. If the 5V line is missing or shorted, a low is provided to pin 85. As a result, the unit shuts down and the power LED blinks 5 times.
6 Blinks SOS: Pin 90 of the MPU IC9003 monitors the status of the SC board. During normal operation, the transistor Q6581 and IC6581 output a low to pin 90. If the SC board becomes defective, a high is provided to pin 90. As a result, the unit shuts down and the power LED blinks 6
6 Blinks SOS: 6 blinks of the power LED may also be obtained from pin 3 of IC9003, the DRV_RESET input. The D board provides the 5V source needed to power the C boards. On the C2 board, the 5V is routed back to the D board via connector C20/C10, C11/D31 causing pin 3 of IC9003 to be high. If 5V is not routed back to the D board, pin 3 of IC9003 goes low. The set goes into shutdown mode and the power LED emits 6 blinks.
7 Blinks SOS: Pin 93 of the MPU IC9003 monitors the status of the SC, SU, SD board. During normal operation, the photo-coupler PC6480 outputs a low to pin 93. If the SC, SU, or SD board becomes defective, a high is provided to pin 93. As a result, the unit shuts down and the power LED blinks 7 times.
8 Blinks SOS: Pin 91 of the MPU IC9003 monitors the status of the SS board. During normal operation, pin 8 of connector SS23 outputs a low to pin 91. If the SS board becomes defective, a high is provided to pin 91. As a result, the unit shuts down and the power LED blinks 8 times.
10 Blinks SOS: The SUB5V and DT9V sources created on the A board are monitored by IC1100. If they are not present at pin 30 and 34, the MPU shuts down the unit. The power LED blinks 10 times.
10 Blinks SOS: The F_STB_15V of the P board, as well as the derived SUB5V and DT9V sources are monitored on the A board for excessive current. If a short circuit is developed in one of the supplied lines, pin 114 of IC1100 receives a high. The SUB5V and DT9V lines are also monitored for excessive voltage. When an over-voltage condition is detected, a high is also output to pin 114 of IC1100. The DT9V is provided to a DC/DC converter to create the BT30V for the tuner. If the BT30V becomes excessive, a high is output to pin 114 of IC1100. A high at pin 114 of IC1100 causes the unit to shutdown and the power LED to blink 10 times.

I have a TH42PZ77U that had this problem. I called Panasonic and was as pleasant as possible and they were, as well. Come to find out Panasonic extended the 1 year warranty to 2 years due to this issue, and they sent someone out within 4 days and they fixed it at no charge. They reprogrammed the new board so that I shouldn't have the problem again. I love Panasonic!