Dead, Battery will not charge
Works with good battery,
Will not work with Adapter
This unit arrived with a common problem that DC jacks presents. However when you continue to use with the defect, it eats the copper around the POS terminal of the jack. In this case the copper had been eaten away, as well as shorting between planes of the motherboards phenolic. So there is only one way to resolve it, by bypassing that section (if possible). The condition of this MA7 was too far gone to be able to bypass.
One picture shows the scorching under the copper, the other shows the current path of the DC In.
Will verify the model number when returning to shop