RAK 4631 No bluetooth signal

LPWAN Nodes
1

I have 2 Rak4631 boards, both working great on meshtastic. I bought a new board to try one on meshcore, after many/several repeated attempts, there is no bluetooth signal what so ever. I have tried both automated Web flashers for Meshtastic and Meshcore, and I have tried it manually. No Signal. Light flashes blue.
I can erase and flash with whichever, zero bluetooth connection available on phone or my tablet, I can only guess I have defective
board or antenna? Now I am getting this msg

Flashing failed!

nRF flashing failed: Error: Invalid ACK sequence. Expected 0, got 7. Please reset the device and try again.

Flashing failed!

nRF flashing failed: Error: Invalid ACK sequence. Expected 2, got 1. Please reset the device and try again.

2

update: it decided to accept meshcore firmware- I dont think the board is stable- a manual copy would fail at 64%- hit retry then it said 100% and it still not working-- I flashed it with meshtastic and that finally worked- it took 3 more attempts of meshcore flashing and it started working now, BT working and connected. I just kept erasing and rewriting to get it working. Solved.