Still disturbing, no change.
WR0003.PRG has no color change in border. It just starts scanner and 3 instructions.
I have created minimal firmware for 407 testing, only scanner and sram IO2 controller + basic functionality.
Please test wr0003, 3x dumps.
Just start C64, there is no booting at all. You should go to prompt immediatelly (no EF, no SD ...).
I'm focusing on C64 data bus.