I'm following your posts because I have the same problems with my ONDA vi30w namely can't add my google account on my tablet, PLAY STORE not opening,can't load secured google websites.
Today, I finally been able to add "ES EXPLORER" to my tablet.
Would you be kind enough to walk me through the process of erasing the HOSTS file as I don't see the HOSTS file in the following files.
You will have to go up (or down?) the file tree all the way to the root, that is: "/", from there to /etc which contains the hosts file, a text file with a bunch of ip addresses in it.
Some setting in ES may prevent you from reaching it by default: modify that. You may have to switch partition, though all of them are grafted onto the same tree at some point (Linux file system), often /mnt/extsdcard, or some sort.
Android has a terminal emulator app that gives you access to that good old command line: get curious about it.
Meanwhile, I pretty much killed my tablet. It simply won't believe the battery is charged up. Even when plugged it with both
chargers! No boot, no recovery. Sigh.