How to check if power board is shot on emerson tv model number lc320em1

Fault at its main digital board. Short circuited component/s at it. Contact any service technician; or the authorized service center. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts.
http://electronicshelponline.blogspot.com/
In most cases, the main board might have to be replaced. If so, a software [firmware] update too might be necessary.

The capacitors on power board must be changed oth

Check capacitor on power board they must be changed 1st

The power supply regulator board to your TV is now working fine, and has no problems at all, as, there is standby light. Check all the other voltages comes out from the power board, to main board. If all of it found OK, the fault should be at its main board.
About blinking of standby/power light;
These blinks (flashes) are fault indication. By the number of blinks occur at one time switch ON, you can get an idea about the faulty circuit stage inside the TV. Count the blinks occur at one time switch ON, carefully. Do it once again, and make sure about the number of blinks. If the flashes are continious, non-stop, the main system control IC should be suspected. If you wish to get more details, check the site linked here. It has blinking codes detail to many brand TVs. Pull up older posts. Check the site in 'Mosaic' view. It will make search easy. http://electronicshelponline.blogspot.com/

what does the set do when you press power? Does the Power indicator come on solid, blinking or etc.

It sounds that the main digital board has damaged. 12 blinks indicates it. if you wish to know more check this link for more details about 12 blinks to Emerson TVs

The power board is shot,

If standby is on, the unit thinks that no signal is being sent to the unit, verify a valid source and try other inputs.....

It could be the power or main board that is giving issues...if your able pull the back off and look for a pin on connector marked PSON or PON...that is line that tells the power board to come out of sleeping and go to work, you should see a change in the voltage when the on button is pushed, if you do then the main is doing its work and its the main if you don't see a voltage change then chances are its the power board

i turned on my tv and it blinks green continuesly. it wont turn off to red light. i unpluged it for 30 min. repluged it and green light comes on and wont stop blinking