Well, i'd prefer that you wait to see if one of our Software Experts posts with some guidance. I'm not a programmer, just an amateur who can play with software/firmware a little. My philosophy is to at least do no harm if i can't help others with a high degree of certainty.

Having said that, if the device was mine i would try to dump some regions using SD text commands. It would be best to try that with the GVN53 boot bin firstly but in a HWID '1036' folder. If that did work, then it might also flash the correct boot information back to the unit. If we can dump regions we can also see exactly which regions have been flashed by the Edge 500 firmware. Region 14 for sure and maybe region 85 [hex OE & 55 respectively]. We can perhaps then work out how to flash the correct bin files to those regions.

If you want to try that, i'll help you by making a kit for you to put on an SD. It's your call, but maybe just wait to see if there are any other ideas from the Navigation Software guys first, say in the next 24 hrs?