I haven’t tried Core 2.5.0 yet so I don’t really know what the issue is. I may have to take a look at the 2.5.0 documentation to see what are the main changes.
It’s possible that maybe it changed flash memory layout. In that case, try to perform a factory reset (while the device is powered on, press and hold the on-board button for at least 10 seconds and release). It will go back to AP mode, and it might work after reset.