Having trouble getting content to appear in the open store app. Just seeing blank page.
It works mostly when I am on wifi, but rarely when using mobile data.
I have no trouble reaching the open store through the UT web browser.
I never edited the /var/lib/ofono/<your_imsi_number>/gprs directly, but I got the APN settings to work by manually entering them into the "System Settings > Cellular > Carrier & APN > APN" section of the UT menu.
I played around with the entries until it worked. Right now, I have one APN heading/settings for "Internet and MMS" and another heading/settings for "LTE." Not sure if LTE is actually working, as I have never seen "LTE" appear on the top task bar.
I did get "4G" to finally appear on the top task bar. One reason why this icon did not initially appear is evidently because my cellular provider is slow or I have bad reception.
Don't know what the "non-shutdown" problem could be.
However, if you tried all the options suggested, both as a normal user and as root (or with sudo), the only other thing that I can think of is to check to your Ubuntu machine and make sure that "/etc/udev/rules.d/51-android.rules" exists.
If that file does not exist, got to the "trouble shooting" section (scroll down) of this page and create "/etc/udev/rules.d/51-android.rules" with the rules listed. Then try everything in the Linux terminal again, both as a normal user and as root (or with sudo).
Here is a post from a relevant thread that gives other commands that might be helpful.
If nothing works, perhaps this OPO unbricking thread can help.
If you do get the phone recognized by your computer, you might want to try ubports-installer, instead of CPT.
Oh, it never occurred to me that @karelq might be trying all of these procedures with the device turned off. @karelq mentioned that the OPO logo would show, so I just assumed that the device was always on during the attempts.
Did you have your device turned on (with the OPO logo showing) when trying all of the above procedures?
The command is "lsusb" (in all caps that would be "LSUSB"). I am pointing this out, because you typed "isusb" ("ISUSB"), which is incorrect.
Also, the idea is to enter "lsusb" at the Linux terminal prompt, without fastboot running.
If "lsusb" doesn't see your device, then you could try it on another machine, or, perhaps, boot a live Linux distro and then try lsusb.
Before you go to the trouble of getting Windows XP, try the terminal fastboot commands after unplugging and re-plugging the USB cable several times. This cable plugging is even suggested in the XDA tutorial that you linked, and it's purpose is to get your system to see the device.
You also might want to try "lsusb" in a terminal with the OPO connected, to find out whether or not your computer is seeing the OPO. If "lsusb" doesn't see your OPO, try another USB cable.
Oh, another thing to try is to press the phone buttons while fastboot says "waiting for device."
Did you try my suggestion?
The idea is that you induce fastboot on your device by executing fastboot commands in a terminal on your computer -- you probably don't need to press any buttons on your OPO.
I had a similar problem with my Nexus 5 I just got the factory logo and no buttons on the device would get me into fastboot, but by connecting my device and running a fastboot command on my computer's terminal, the fastboot screen appeared on my device.
I am not familiar with the cpt installer, but if you have fastboot on your computer, connect your OPO with a USB cable. Then, type some fastboot command into your computer's terminal, such as "fastboot oem unlock". Hopefully, the fastboot screen on your OPO will appear.
If nothing happens, try the same commands as root (or sudo) in your computer's terminal.
If you get ffmpeg up and running on your device, you might want to try merely playing the original video with ffmpeg's player -- "ffplay".
Also, you might want to try mplayer/mencoder. It's command line, like ffmpeg, but it likewise has various GUI front-ends.