Rock64 - can not connect via store's USB-to-serial nor see (if) booting.

[tllim]

My attempts (five steps) and my question follow.


1.    With the store's USB adapter, I have flashed eMMC 16GB using Etcher on a Windows 7 laptop with the image in the second link that follows.
https://etcher.io/
https://github.com/ayufan-rock64/linux-b...m64.img.xz

2.    I have put the eMMC in my Rock64.

3.    I have wired and connected the store's USB-to-serial adapter and my Rock64.
    On USB-to-serial adapter (pins at right):
Jumper is south (facing me) and set on east pair of pins, S1 and 3V3.
GND: black (goes to GND on Rock64's PI-2 bus)
RTX: brown (goes to TXD on Rock64's PI-2 bus)
TXD: white (goes to RTX on Rock64's PI-2 bus)
3V3: red (most northward cable) - NOT CONNECTED to Rock64
    On Rock64, PI-2 bus (long set of pins) is most northward; HDMI is south; GigE/USB is east.
    Bottom (southern) pins are numbered odd starting at 1 (going to 39); top (northern) pins are numbered even starting at 2 (going to 40). See,
    bottom (southern) pin (this is the leftmost one):
1  3.3V PWR - DO NOT use. See Serial Console for the Rock64 - https://forum.pine64.org/showthread.php?tid=4928 - NO EXPLANATION given for why!
    top (northern) pins:
6  GND: black (goes to GND on USB adapter)
8  TXD: brown (goes to RTX on USB adapter)
10 RTX: white (goes to TXD on USB adapter)
    Executive Summary:
USB    Rock64
GND <---> GND
Rx <---> Tx
Tx <---> Rx

4.    I have tried putty on Windows 7 (to no avail), and then minicom on Debian, and now Raspian.
    Upon plugging in USB-to-serial adapter on Debian, I saw/see a red led (and iirc, a light blue led next to it, at  least on Debian)
# dmesg | tail -n 10
    gave
# usb 6-1: ch341-uart converter now attached to ttyUSB0
    I issued
# minicom -s -D /dev/ttyUSB0 -b 1500000
    which returned (for both Debian and now Raspian)
Welcome to minicom 2.7

OPTIONS: I18n
Compiled on May  7 2017, 05:18:49.
Port /dev/ttyUSB0, 14:19:34

Press CTRL-A Z for help on special keys

5. I plugged in power which lit an additional led on the Rock64. I see no change at my console (minicom).

ADDENUM: blue led is lit @RPi too; HDMI connected but monitor shows nothing.

QUESTION: What did I omit/do wrong, or what should I be doing next (or should have done before)?

Please post a photo on your board and USB-to-serial adapter connection.