Power light blinks, 620, unplugged and plugged back in, same thing. it turns off eventually, but when I hit the power button, starts blinking again

There's a couple of things you can try.

1. Unplug the set and disconnect everything connected to it (DVDs, etc.). Wait five minutes. Plug the television back into the wall outlet, and try to turn it back on again using the remote control or the "Power" button on the unit itself. If the television starts up without the blinking light, turn it off, reconnect your devices and turn it back on again. If you still see the blinking light, perform a factory reset.

2. Factory reset.
Point the remote control at the television, and press and hold the "Up Arrow" button. At the same time, press and release the "Power" button on the television. Your television will reset to its factory settings, and the red light will no longer blink.

If neither of these work you will need factory service.

These blinks [flashes] are fault indication (Error Codes). From the number of blinks occur at one time switch ON, you can get an idea about the faulty circuit section inside it. This will make repair easy. These are called blinking codes. Make sure about the exact number of blinking of the standby/power LED, by switching On & OFF the set, for at least two times. Count it carefully. If you wish to get some details, check the site linked here. It has details about blinking codes, and fault locating procedure, to many popular brand TVs and other devices.
http://electro-medical.blogspot.com/
http://electronicshelponline.blogspot.com/
If blinks continue without any pause, the main board is faulty.
Search the site by type in the "brand name" to your device, in the "Search box at the top right of the display window of the Homepage" to get gathered related posts.

the blinking power indicator is actually a error code. How many times does it blink as I can assist you if you let me know how many times the led blinks

make sure tv not in standby mode

The 3 blinks is a error code for the convergence circuit. You can get the convergence repair kit for your model at the following link which contains both Convergence ICs and all six feed resistors and they include step by step instructions with pictures that show how to do the repair yourself. Heres a link to the proper kit for your model Panasonic.
http://servicemanuals.vstore.ca/product_info.php/pName/panasonic-projection-tv-convergence-repair-kit-2/cName/convergence-repair-kits

i have fixed 3 of this tv, with that exact problem in the last 2 weeks, needs a power supply, you can try to unplug it again, plug it in, hit the power button, as soon as it turns green, unplug it again, after 15 seconds , plug it back in, if power doesnt turn on by itself, turn it on, if it turns red again, emediatily hit power again, may have to hit power a few times in a row, but most of the time you can get it to come on this way, once it is on, it should run ok, until you turn it back off, but not a fix, needs power board

I left if off and unplugged for a few hours. When I plugged it in it started working again. My recommendation if this happens to you is to just unplug it all and let it stand for at least 4 hours and then plug it back in.

Good Luck

i went to turn on the tv and the power button don't work

Hmm I tried unplugging it for a while but I will try this again tonight since it will be unplugged for about 24 hours.
Thank you McColp for the info..

I have a service guy coming tomorrow, maybe this will work before he comes! I appreciate your help!
take care
Maria

You could have gotten an electrical surge that put your set into a shutdown condition and unplugging the set and letting the Microprocessor reset will fix this problem if it dosent blow out the main power regulator as you still or might I say have a regulator IC problem. IF THIS PROBLEM HAPPENS AGAIN MORE THEN A FEW TIMES WITHIN A SMALL TIME FRAME I WOULD HAVE THE SET LOOKED AT BEFORE THE REGULAOR BLOWS SOMETHING OUT!!!!