Does the 10 blink issue apply to Panasonic plasma TV model TC-P50G25? Will replace the main A board fix the power issue? Thanks.

A 10 blink code on a Panasonic plasma TV typically indicates an issue with the power supply board. You will need to consult the service manual or contact a qualified technician to identify the exact part that needs to be replaced.

The power supply could be at fault.

Did you try holding the power button down for about 30 seconds and release it? There are a lot of videos on plasma sets like yours that have this issue. I would wager the power supply before the main board.

Here is a video on this.

Sounds like main digital board fault. 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.

Could be bad power supply not giving enough voltage/current to the board. Try switching that and see if that helps

With 10 blinks it could be any of the following boards, the blinks tell you that is is a power problem

A-Board TXN/A1LPUUS
SC-Board TXNSC1LPUU
SS-Board TXNSS1LPUU
P-Board ETX2MM806ASH

10 blinks for this tv is not always an A Board issue. It can be a problem with the power board as well. A technician should look at the set to dertermine where the problem lies otherwise it is just a guessing game of inni minni miny moe.