I found this answer from a previous post:
Hmm, well that's not great news. A 2-3 error code indicates a problem in the horizontal deflection and high voltage circuits, and is a fairly uncommon problem with this TV.
What you need to do is pull off the speaker grill, and remove the access panel behind the speaker grill. Get a flashlight and look carefully at the 3 circuit boards near the front, under the tubes. There have been problems where cooling fluid from inside one of the tubes has leaked out. If you see any fluid on the right most PC board, most likley your set is trash. If you see any on the middle or left boards, it may be ablet ot be fixed.
Of course, there are many other problems that will cause this error code, and if you have electronics experience and (ideally) an oscilloscope, I can give you some ideas. You'd also need a service manual.
Otherwise, you will have to call a Mits tech.
Let me know if you have any other questions or would like to try to fix it yourself, and thanks for using JustAnswer!
Read more: http://www.justanswer.com/questions/1wknq-mitsubishi-1080-series-model-ws-65809-tv-worked-fine-yesterday#ixzz0bTmPPnLS
From the back of the TV, the green board on the left did show like a water stain and some rust and white corrosion. So, does this mean it's beyond fixing? How much would a new board and, I'm guessing, lamp cost?