B2A8S20P loss bluetooth connexion and desappear from availlable devices

[ttiburst]

The problem :

1) i reset the bms, with the push button,
2) i can see the bms in the bluetooth list,
3) i can connect it,
4) after few minute the connexion is lost,
5) when i go back and launch the scan to reconnect the bms does not appear,
6) impossible to get connect until reset.

Please help me