I have one new observation.

When I try to update Vanilla in Update mode, it find and refuese the device connection. - the USB symbol is shown, I press the Enter on keyboard with command on Terminal and symbol of USB on N900 display is gone.

So, cold flash it cannot do, because it cannot see the device. But Vanilla cannot do, because it refuse it. After 2 minutes the device (if is in R&D mode) change on the screen - some information about kernel, product, hw-build are added (green font) and flashing with Vanilla STARTS! And ends with success.

But, the problem is stil the same - cannot boot the device, only NOKIA is shown.