Help pls~Desktop (xfce4/lxde/gnome/i3) installation problem. Install_desktop.sh faild

[yours_david]

Hi Pine64 community, 

I have been very happy to have Rock64 running openmediavault to manager my 3 HDDs for share, 2 HDDs sitting on USB3 HDD dock for non-raid share, 1 HDD USB2 running cold backup. Now I would like to install desktop, e.g. xfce4/lxde/gnome/i3, on top of my OMV image. I run "install_desktop.sh" script from "/usr/local/sbin/" after searching through forum and internet. 

The installation progress get stuck while fetch plex, the error code is in below. The full details list at bottom for better reading.

Code:

E: Failed to fetch https://downloads.plex.tv/repo/deb/dists/./public/InRelease                     Unable to find expected entry 'main/binary-armhf/Packages' in Release file (Wron                   g sources.list entry or malformed file)
E: Some index files failed to download. They have been ignored, or old ones used                    instead.

My firmware based on 0.6.31: jenkins-linux-build-rock-64-209, which was upgraded from 0.6.28: jenkins-linux-build-rock-64-197 by running "sudo apt-get update -y & sudo apt-get install linux-rock64 -y". 

As a linux noob, I tried what I can but still failed to install xfce4 then run KODI while running OMV at background. 
I checked install_desktop.sh trying to comment off fetch plex in order to continue such installation, but I can't find anything. 
I also run "apt-get install xfce4", but don't know how to run xfce4. 

Can anyone help me to run OMV+HTPC Kodi solution on my rock64 NAS build? Two questions.

Q1, how to fix install_desktop.sh?
Q2, without that .sh strip, how can I install xfce4 and kodi then run based on OMV rock64 firmware? Thank you for any advise.

Cheers, 
David

Full log which run install_desktop.sh

Code:

root@NAS-David:/usr/local/sbin# install_desktop.sh xfce4
Get:1 file:/var/cache/openmediavault/archives  InRelease
Ign:1 file:/var/cache/openmediavault/archives  InRelease
Get:2 file:/var/cache/openmediavault/archives  Release
Ign:2 file:/var/cache/openmediavault/archives  Release
Get:3 file:/var/cache/openmediavault/archives  Packages
Ign:3 file:/var/cache/openmediavault/archives  Packages
Get:4 file:/var/cache/openmediavault/archives  Translation-en
Ign:4 file:/var/cache/openmediavault/archives  Translation-en
Get:3 file:/var/cache/openmediavault/archives  Packages
Ign:3 file:/var/cache/openmediavault/archives  Packages
Get:4 file:/var/cache/openmediavault/archives  Translation-en
Ign:4 file:/var/cache/openmediavault/archives  Translation-en
Get:3 file:/var/cache/openmediavault/archives  Packages
Ign:3 file:/var/cache/openmediavault/archives  Packages
Get:4 file:/var/cache/openmediavault/archives  Translation-en
Ign:4 file:/var/cache/openmediavault/archives  Translation-en
Get:3 file:/var/cache/openmediavault/archives  Packages
Ign:3 file:/var/cache/openmediavault/archives  Packages
Get:4 file:/var/cache/openmediavault/archives  Translation-en
Ign:4 file:/var/cache/openmediavault/archives  Translation-en
Get:3 file:/var/cache/openmediavault/archives  Packages
Ign:3 file:/var/cache/openmediavault/archives  Packages
Get:4 file:/var/cache/openmediavault/archives  Translation-en
Ign:4 file:/var/cache/openmediavault/archives  Translation-en
Get:3 file:/var/cache/openmediavault/archives  Packages
Get:4 file:/var/cache/openmediavault/archives  Translation-en
Ign:4 file:/var/cache/openmediavault/archives  Translation-en
Hit:5 http://security.debian.org stretch/updates InRelease
Hit:6 http://ppa.launchpad.net/ayufan/rock64-ppa/ubuntu bionic InRelease
Get:7 https://download.docker.com/linux/debian stretch InRelease [39.1 kB]
Get:11 https://downloads.plex.tv/repo/deb ./public InRelease [3408 B]
Hit:12 http://packages.openmediavault.org/public arrakis InRelease
Ign:14 https://dl.bintray.com/openmediavault-plugin-developers/arrakis stretch I                   nRelease
Ign:15 https://dl.bintray.com/openmediavault-plugin-developers/arrakis-testing s                   tretch InRelease
Ign:16 https://dl.bintray.com/openmediavault-plugin-developers/arrakis-plex stre                   tch InRelease
Get:17 http://deb.ayufan.eu/orgs/ayufan-rock64/pre-releases  InRelease [1253 B]
Ign:18 https://dl.bintray.com/openmediavault-plugin-developers/arrakis-sync stre                   tch InRelease
Hit:19 https://openmediavault.github.io/packages arrakis InRelease
Ign:20 https://dl.bintray.com/openmediavault-plugin-developers/arrakis-docker st                   retch InRelease
Hit:9 https://apt.syncthing.net syncthing InRelease
Get:21 https://dl.bintray.com/openmediavault-plugin-developers/arrakis stretch R                   elease [4389 B]
Hit:21 https://dl.bintray.com/openmediavault-plugin-developers/arrakis stretch R                   elease
Hit:8 http://cdn-fastly.deb.debian.org/debian stretch-backports InRelease
Ign:10 http://cdn-fastly.deb.debian.org/debian stretch InRelease
Hit:13 http://cdn-fastly.deb.debian.org/debian stretch-updates InRelease
Hit:22 http://cdn-fastly.deb.debian.org/debian stretch Release
Get:24 https://dl.bintray.com/openmediavault-plugin-developers/arrakis-testing s                   tretch Release [4389 B]
Hit:24 https://dl.bintray.com/openmediavault-plugin-developers/arrakis-testing s                   tretch Release
Get:26 https://dl.bintray.com/openmediavault-plugin-developers/arrakis-plex stre                   tch Release [3540 B]
Hit:26 https://dl.bintray.com/openmediavault-plugin-developers/arrakis-plex stre                   tch Release
Get:29 https://dl.bintray.com/openmediavault-plugin-developers/arrakis-sync stre                   tch Release [3540 B]
Hit:29 https://dl.bintray.com/openmediavault-plugin-developers/arrakis-sync stre                   tch Release
Get:31 https://dl.bintray.com/openmediavault-plugin-developers/arrakis-docker st                   retch Release [3540 B]
Hit:31 https://dl.bintray.com/openmediavault-plugin-developers/arrakis-docker st                   retch Release
Fetched 43.8 kB in 8s (5031 B/s)
Exception ignored in: <function WeakValueDictionary.__init__.<locals>.remove at                    0xf6ca1468>
Traceback (most recent call last):
 File "/usr/lib/python3.5/weakref.py", line 117, in remove
TypeError: 'NoneType' object is not callable
Exception ignored in: <function WeakValueDictionary.__init__.<locals>.remove at                    0xf6ca1468>
Traceback (most recent call last):
 File "/usr/lib/python3.5/weakref.py", line 117, in remove
TypeError: 'NoneType' object is not callable
Reading package lists... Done
E: Failed to fetch https://downloads.plex.tv/repo/deb/dists/./public/InRelease                     Unable to find expected entry 'main/binary-armhf/Packages' in Release file (Wron                   g sources.list entry or malformed file)
E: Some index files failed to download. They have been ignored, or old ones used                    instead.