RAK4631 can't connect over Bluetooth

I bought a brand new RAK4631
Firmware installed on the board: v2.5.20.4c97351
I used the drag-and-drop method.
The device is attached to W10 via USB for configuration.
I can’t access this device using Bluetooth.
I see this device on the Bluetooths page W10:
image
However, I don’t see this device when I try to connect it to my mobile phone or notebook laptop.
The device has a battery attached, and it is using serial; it shows that it has the right voltage:

image

When I detach the battery, I can’t connect to this device (the heartbeat LED still blinks, but it’s not very bright). I measured the battery’s voltage, and it is over 3.8V.

What is wrong?

Additionally, when I try to disable the heartbeat LED, I get this message:

We are not developing or maintaining the Meshtastic firmware, we cannot give support for problems with Meshtastic.

No idea what a W10 is.
Regarding heartbeat LED disabling, I have no idea what the error message means, please contact Meshtastic for an explanation. They are the developer and maintainer of the Web Client.

If you see the Bluetooth in the W10, that means the Bluetooth of the RAK4631 is working. I don’t know why your phone or laptop doesn’t see it.

W10 = Microsoft Windows 10.