Hi Kevnm67 and All,
While I'm not sure what the problem is, some dealers do not order their ADC/DMIC-20's with the "consumer channel status" settings. I don't know that the MD would be sensitive to this, but as a consumer device it may. If your DMIC does not have a sticker on the bottom that says "consumer channel status," it may be sending "professional channel status" which contains no channel status (ie. SCMS) information and the receiving deck may default to "no signal" or "copy prohibit" (if it behaves the same way the D7/8's do).
If the problem seems to be intermittent power, try spreading the pins inside the DC input jack on the DMIC. Be careful as these can break. This is the same issue as quite a few folks have experienced with the V3.
I would not be too concerned that it you may have harmed your mics because the deck has no way of knowing what type of audio (noise, music, etc...) is supposed to be coming in and it will not descriminate. Further, while it is a good idea to connect and disconnect mics with phantom off, it almost never harms anything, especially the mics.
As others stated, Graham-Patten support is some of the best in the audio world.
Keep us posted on how it goes.
Happy Recording,
Marc