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I had this occur on my MakerBot Replicator Dual after I tried repairing a blown voltage regulator. If you refer to the previous link to my SE question, pay attention to the comments of Ryan's answer where it is explained that (in my case at least) the main processor was damaged and therefore couldn't properly load the firmware. The machine was able to load just enough to initialize the chip on the LCD screen, but since the main boards processor was blown, couldn't load the firmware to send commands to the screen and continue the boot sequence.
I'm not certain that you're encountering the same EXACT issue, but you have all of the same side effects that I did. Basically, if you're not pro with electronics, your board is bricked. Otherwise, you might be able to salvage the board by replacing the processor, but there's no guarantee that something else isn't wrong or that the new processor was installed correctly.