I just happen to know a "shade tree" mechanic.....
This will not make things worse and may just solve your issue. Cross your fingers hold my beer and try this......
1. Set up to bleed your brakes.
2 When ready Turn on the ignition and leave on. This will activate the ABS system
3.Go to wheel furthest from master (right rear) and open the bleeder. This should kick the ABS pump on and pump the air out through the bleeder.
4.Bleed the remaining slaves.
5. Turn your key off and use the power bleeder to bleed all brakes.