Without connection to PC. Only chance JTAG.
This is an Security Feature from Qualcomm... if you kill/interrupt Bootloader chain...
Without JTAG, NO chance.
Elco has both.
JTAG + TestPoints and enough experience.
Also future solution, only via JTAG Hardware + high skills.
Maybe other user can offer JTAG repair for Omnia... in your country...
Good Luck.
Best Regards