My suggestion is to reorder this into a flow pattern.  Assuming Avionics master is on:

1. Battery Selector - Bus
2. Battery On
3. Check Metering
4. External Power Selector or APU Gen set
5. Turn on External Power selector or start APU
6. Check APU Gen - Metering or, before using external power, check metering
7.  Perform visual flow on overhead though each vertical segment.

How I do it and I will upload a raw vid (love raw since mimics real life rather than edited sequence or rubbish) on visual flow patterns.  But this is in the manual documentation provided by Captain Sim.