That usb controller does not control the power line. In general, USB power and ground are always connected. If they weren't, memory sticks wouldn't have input power, and would not function. Sounds like you need to trace the 5V power on that board and see where it stops, if it's even present at all.
Corrosion on PC boards is always bad. Pictures would help a lot on that. Given your power symptom, it could easily be something like leaking capacitors that need to be removed, board repaired, and replaced.