D4H | RAK7248 Lost operating system

I received last Monday WestGate Developer D4H | RAK7248 for TTS fundamentals training. this morning I test Balina with another card. No success ok, I put the original card back. Suprise no rakwireless no config no ChirpStack no Ethernet.
I downloaded the RAK7248_Latest_Firmware firmware.
I tried putting it back with balenaEtcher on a Samsung card but failed each time.
I looked after a procedure but nothing conclusive.
I am looking for a good soul who could help me get out of this bad situation.
Thank you.