If you read around i had the same issue on my S802 lol,
After i re-solder that pos hdmi port module, boom picture was back, i used a clamp to push it firmly on the pcb so i could solder ok all the cold joints.Its a known issue if you look around.
Thank You. Tomorrow morning I will try to fix 
I turned crazy about that.
Hi
I have an MXIII-G (Nextron - M82G V2.1 Board)
Suddenly, while it was working, it got bricked.
From some videos on youtube, I managed to get it started again, but after splashscreen I get a black screen.
I've tried updating the firmware several times with those on the chinagadget site but the result has always been the same: Splashscreen, often with altered colors and then black screen without vital signs.
Now after the next failure, I decided to install a Linux distribution.
The predominant use will be with Netflix and Amazon Prime.
With the image linked on I booted the system, then i got the splash screen then everything went black again but suddenly I had some screen output flashing slowly. with a near Salomonic patience I added password for WiFi connection and enabled ssh.
with "installtointernal" command I copyed system to internal Nand, and rebooted.
Always black screen.
With dmesg I've got this report, seems everything working fine except for some
[amlogic] ##### cec write error! #####
obviously I've got no video output ... any tips ??
Thanks to everyone in advance for the help, and sorry for my English
