I have the same issue.
I can’t upgrade my firmware (1.5). I have made many attempts with different sd cards and with the firmware inside the root directory. Moreover, I can’t do the OTA upgrade, it doesn’t connect via hotspot with my iPhone 17 pro. I tried to disable the bluetooth before turning on the device but nothing, if I insert a correct password or an incorrect password is the same, nothing happens, no indication on my phone that a device is connected with the hotspot.
I tried also to connect with another WIFI that is close to the device, using a wrong password in this case since it’s not my wifi and I don’t know the password but still no error is raised.
Any suggestion?