LG 60PA6500 won't start

My LG 60PA6500 plasma TV shuts down as soon as I turn it on. The TV makes a humming sound when I switch it on and then turns off almost immediately. The problem started after I accidentally left the TV on for about a week.

I tried the following:

1. The TV (the red light on the Main Board) stays on if I disconnect the Z-Sus board and the Y-Sus board from the Power Board. There is a flashing green light on the Logic Board.

2. The TV (the red light on the Main Board) stays on if the Power Board is connected to the Z-Sus board only (without the Y-sus Board). There is a flashing green light on the Logic Board.

3. However, when I connect the Y-Sus board to the Power Board, there is a humming sound coming from the 2 heat sinks of the Y-Sus (connected to a row of Mosfets) and the TV shuts down.

4. However, when I disconnect the power cable from the Y-Sus board but leave the ribbon cable from the logic board to the y-sus connected, the red light on the Main Board stays on and the green light on the logic board flashes.

I also checked the power coming out of the Power Board (without Y-Sus connected)

M5V reads 5.2V

VA reads 55V

VS reads 205V

After I connect the Y-Sus, the readings are

M5V reads 5.2V (briefly before shuts down)

VS not able to get reading before TV shuts down

I reckon the problem is with the Y-Sus board and if so, what do you reckon is wrong with the Y-Sus board?