Welcome Tete_360 to Android Forums!
I would like you to have your Computer, USB Plug, not OTG, and Xtouch phone.
If you would like to flash it via PhoenixSuit (A convinced flash firmware tool) or Live suit (A normal), Then download the flash firmware:
http://pan.baidu.com/s/1nt0q7Lv and
http://pan.baidu.com/s/1c0GOnc8
Older:
http://pan.baidu.com/s/1qWDHFQW
Then I would like you to have the PhoenixSuit or Livesuit installed on your PC, I am not sure whether the older version or newer version of flash.zip have Android 5.
This problem that you have faced is the poor network signal or Google can't reach it.
You open PhoenixSuit, enable USB debugging, in Developers tab after you have clicked the Build number 7 times on About phone.
You plug your USB to your computer that recognizes it, then put the jack of charger inside the charging port, then PhoenixSuit recognizes it.
You click Browse, then navigate to your downloaded ROM for Xtouch device, and press the volume down and holding it, then press the power button 15 times after you shutoff your tablet, then you should have prompted that you have to format or not, Maybe click Yes and your data would be wiped, putting the new OS into your phone.
If formatting doesn't prompt, turn on your phone then wait for few minutes, to boot, then click and hold the volume down button, then press the power button 15 times as your screen is not turning on.
After your ROM have been succeeded, you must restart your device, then your OS have been updated.
How to download from pan.baidu:
This tutorial shows you how to download the file.
Glad your OS should not bootlooped.
Cheers, Yazan .