Try the Bluetooth classic library instead, not the BLE.
Or try a serial terminal emulation program, see if you can at least connect to the device without being disconnected.
If that is successful, then use Bluetooth (Classic) rather than Bluetooth (Low Energy) - they are different and not compatible, other than coexisting - and every few seconds alternate beween sending these two four-byte commands:
'backlight_on': b'\xC0\x47\x00\x20',
'backlight_off': b'\xC0\x48\x00\x62'
or in B4Xese:
Dim BacklightOn() As Byte = Array As Byte(0xC0, 0x47, 0x00, 0x20)
Dim BacklightOff() As Byte = Array As Byte(0xC0, 0x48, 0x00, 0x62)