I just redid the process in the tutorial, then uploaded seperately the cust file with SE tool in MISC files like you said (in contradiction to what I said before in the end I used the HB1-06_Gen_CDA102568_12_R8A_GENERIC_EUROPE_3, since it is sim-lock free), and then removed the simlock.

All works fine now! I would like to thank you guys for your help!

Cheers,
Vincent