Power distribution panels
There are 17 Remote power dist panels all over the aircraft. One is located exactly in the fire damaged area. But if you are saying the aircraft had no GPU and APU was also not running, then there is no power at these panels. The panels have 115V AC and 28V DC power supply.
This info about APU/GPU may not be correct. Some one mentioned the aircraft was getting ready for a tow to Departure area from remote parking. In which case the aircraft will be powered, most probably from the APU.