v1.4 not booting into flash mode

[anthonyangel]

I'm trying to flash a v1.4 board, but I can't get it to boot in flash mode. I have it connected up as follows:

FTDI Board
Rx --> Tx
Tx --> Rx
GND --> GND
GND --> GPIO0

Using ESPtool I'm getting the error: A fatal error occurred: Invalid head of packet ('\x00'), I've also tried with PIO and the recommended settings from the Readme with Arduino IDE with similar results.