Maybe I'm being silly, Jumpstart, but are youi sure the one that didn't work was the JAP version?

Anyway, as you've now got the Origachip, here's what happens on my SCPH 15000 on the no dongle version:

1 DVDRX PAL boots fine!!!
2 DVDRX JAP (backup) boots fine behind DVDRX PAL!!!
3 DVDRs boot behibd a large TOC Original DVD game because I retained the old modchip.