Yes this maple had serious sunburn damage. At this stage it is starting to rot and the borers are helping to break down the damaged tissue. Start by scraping off all the dead tissue. If the bark resists and is hard to remove, just leave it on. Again spray the wound with a copper based fungicide to minimize rot. This tree might be able to callus much of this wound like the other tree did. Borers would need a spray of Spinosad on the trunk to control them.
These trees were probably planted in the open with a south and west exposure which is pretty tough on them if they are not well watered all summer. Water and mulch them well and hopefully they will come back some.