1. Trace back from the harness connector end and try to determine where the connection is broken (not fun).
2. Determine with a meter or test light which of the 2 connector pins goes to +12v. Verify all connector pins for all injector connectors have that continuity. Wire in a new +12v feed line to one connector - it will feed the rest. Be careful doing this update - don’t want to fry your ECU by connecting directly to the ECU side of things.