Last night I installed Ubuntu Touch on the JingPad C1. Thanks for all of the posts here as this install took a lot of attempts.
A note: I unlocked the bootloader in Windows and ran the up-ports installer on Linux. I did not try to unlock the bootloader in Linux.
Thanks again for all of the pointers. Now, on to the donations page. The best way for individuals to support free and open source software.
@moem No I don't want to sell it. I am going to keep it because I think UT will be very functional soon enough.
When I first installed 16.04 about a year ago the keyboard worked straight out of the box. Somewhere around October or November it didn't work anymore. I am not sure when or if it was caused by an update because I simply didn't use the tablet much.
Last night I reflashed to stock Android and the keyboard is now working. Interestingly, the keyboard has some issues in Firefox but the keyboard is functional in Brave Browser, Mobi Office Suite, all Google apps and others.
I flashed back to stock Android 10 that had been recompiled to accept open-gapps and NikGapps. I choose to use NikGapps. I have a working Android 10 that is compatible with Google Play Services and Google Play Store. I have installed Google Photos, Maps, GBoard, Mobi Office Suite, Brave Browser and others. I added Firefox via a downloaded apk.
This tablet is now a fully functioning Android 10. Sadly, as much as I support Linux this tablet will stay Android for a while longer. JingLing Linux is gone and UB Ports just isn't ready yet for my needs.
Very possible this is a hardware problem. I have reinstalled the original android OS to the JingPad to see. If I have more issues I will start another thread.
I upgraded to 20.04 last night and this fixed the rotation problem.
But, I still don't have the external keyboard function. 
Has anyone flashed the JingPad back to stock? I have the application Research Download and the original .pac file plus another .pac that was complied to use open gapps. I have 16.04 (OTA-24) installed.
Following the instructions from JingPad company I get to the recovery screen as directed (this is the UB recovery screen) engage the Research Download but nothing happens. I've waited 10 minutes and tried this several times. Other people have reported that flashing back to stock works.
I am not sure what is necessary to do. Do I need to wipe some or all partitions? Factory reset? What state should the recovery application be in?
If it matters, I cannot reboot to bootloader from recovery either by adb commands or from the UB Ports recovery screen.
I am doing this in Windows because Research Download is a Windows app. In command prompt, the JingPad is listed as in recovery mode.
Developer mode is on.
What am I missing?
My JingPad does the same thing. Maybe 1 in 20 boots the rotation will go to landscape mode in the supplied case the rest are in portrait mode when it should be landscape. I do not know about booting in the keyboard as my JingPad keyboard stopped working a few months ago.
Agree: pointless JingPad
Edit: the JingPad may have issues but thanks go to the devs working on this. The JingPad company left us with nothing and UBPorts came to the rescue. Hopefully things will get better in time.
@ian
Thanks for the info. I did not know this.
@ian
I use a USB 3 on my computer to connect with the JingPad. I did find that the cable supplied with the JingPad did not work. I used a cable that I knew worked with my Pixel 4a.