I just went through the process. It did work, but not without some extra steps.
- After holding power + vol down, I had to wait for a number (5 or 6 ) blinking pattern to stop before the bootloader menu appeared.
The pattern goes like this :
1) 11 regular, slow blinks
2) fast on-off-on
3) a long off
After the bootloader appeared, I did "START" immediately, the phone showed a google logo for few seconds, shut off and started blinking again.
I repeated the whole sequence. That time, the cycle happened only once and I was back to the bootloader menu.
I left the phone in boot menu screen for 1/2 hour, and then the START finally worked.
Maybe this can help some people for who the method doesn't work immediately.
Philippe