I have a motherboard I acquired cheaply, but which does not even post on poower
on. This was in a case, and had the 4 pin power connector plugged in 90 degrees
wrong so that the pairs of 12V and GND connections would each receive one 12V
and one GND supplied from the power supply. I suspect, that the internal board
connections to this connector could have fused. What I'm wondering, is if there
would be any possibility of determining if this is so, and if it can be
repaired.

If I turn on the board with the large power supply connector installed, and the
4 pin connector disconnected, I see no significant voltage on either 12V lead of
the motherboard 4 pin connector, so voltage is not getting through to the 4 pin
connections from the main power connector.

The board is an Asus M4A87TD EVO

Any ideas about how to test my hypothesis, or perform repairs?