- Edited
I unpacked the 3.6 for dudu7 and the FYT.prop simply contains sys.fyt.bluetooth_type=7. Your sys.fyt.bluetooth_type=0 is a bit strange.
Anyway: You can downgrade by first running an up-to-date lsec6318update and a totally empty file "lsec-downgrade" in the root of your USB stick. Do not add anything else. "flash" that one. Then flash again with 3.5.