The Problem you are describing is due to the Capacitors in the DM module of the set failing, and not allowing the DM module to boot up.
You are encountering the "famous" problems of the Mitsubishi v26 and v33 chassis based tv's - Mitsubishi has used these chassis in almost ALL of the DLP tv's they made, and they are loaded with problems..In my opinion they are complete lemons.
As a matter of fact-- I just tossed a WD-52525 in the dumpster a few weeks ago - the customer didn't want it back, and I could not even justify spending the time on it to keep it for myself...It was sad to have to do it though..
There are almost two dozen capacitors in this set that are located on the DM board, Format board, Power supply and the Terminal boards that were cheaply made, and go out of specs .... until the capacitors on the DM board go completely bad and the tv will simply sit flashing the green timer led and do nothing. Which you have experienced as your "first" symptom.
This is known as the "flashing green light of death" -- You may want to google "mitsubishi dlp lawsuit" I have heard of several class-action suits against mitsu for these sets.
Mitsubishi is supposedly offering a refurbishment service on these chassis' and I have heard several different prices - from $350 to $850... you may want to give mitsubishi a call and see what they say, but honestly for that kind of money, I would recommend investing it in a new set, because you could STILL have problems with the light engine, which are common as well.
I have worked on several of these sets, and I now just refuse to touch them due to the fact that they are so problem riddled--between the bad capacitors in the chassis, the light engine problems and the bad thermistors in the set, (not to mention how long the DLP lamps last) ....when you DO repair one, and something ELSE fails 2 months later, it makes it look like it "wasnt fixed right the first time"------ It's a complete customer relations nightmare!
I really wish I could give you better news, as I have to say that a 4000.00 tv should last a bit longer than 3 +- years....
I hope I have given you helpful information, but if you want more IN DEPTH infromation, let me know...I have PAGES on these sets...
Here is a thread you might also want to check out regarding the problems related to these sets.
If you need more info, let me know!