Yes, no need to give up yet. It may be that there is wrong data in region 5 (i.e. 0971's instead of 0972's) and that foreign bootloader isn't capable of booting the device.

Try to load only the boot.bin from 0972 firmware as 097201000630.rgn. Use RGN_Tool to open the GCD or RGN fw file, uncheck the second and third fields leaving only the first one checked, and then save the boot.bin using the "RGN" button. Flash that using updater.exe to see if it loads successfully and if it can then the device might boot up.