Thanks for the feedback.
Make sure you know how to debrick your device if something goes wrong:
- can you try the factory image again over the WEB interface?
I've re-uploaded the 7500v1 with minimum packages. (minimal size). May be the image size was the problem as the other part of the build is basically the same.
If it is working with the standard openwrt image. It should be working with this customized test image too.
I have one additional question:
- Have you tried sysupgrade -n openwrt..... after you flash it first with the standard openwrt?