[General Questions and Answers] Znayx:
Hello all, I have run into some unfortunate trouble that I'm sure many of you have heard about before. I shall start with the short and sweet for those who know about this, and then move onto a detailed description of the events and steps I've taken. Put simply, for those in the know: My phone always runs into the "Connection problem or invalid MMI code" error when attempting to access the hidden Service Menu.

The details:

My phone, an LG G3, used to be working well, without any significant issues for a significant time. Then, one day, it was acting slowly for no clear reason. I decided that a reboot would be the most likely help. When my phone came back on, it was very hot. I also noticed that I could no longer double-tap the screen to turn it on -- a feature called KnockON. This works also to turn off the screen, when on the lock or home screen. I restarted the phone and set it to cool down near a vent, hoping this would set everything as it was before. The issues remained, and those issues were that a few features, just a small handful that I observed, were switched. If they were disabled, they were turned on, and if they were enabled, they were turned off. Not many, so I dealt with all of them quickly. Examples: The battery percentage was hidden, when I had it showing. Vibrate On Tap was active, even though I leave it off. And most importantly, KnockON, a feature not in an openly accessible menu, suddenly no longer worked.

After some research, I discovered that those seeking to disable the KnockON feature can go through the Dialer, by typing in it special codes called MMI codes, which would depend on the phone model, primarily. The site stated that what needs to be entered into the Dialer is: 3845#*XXX# where XXX is the model number of the phone, or 855 is it is an international model. Apparently, this model number actually varies by Provider. AT&T uses 850, T-Mobile uses 851... This is irrelevant, but slightly interesting. By searching in the regular menus, I determine that my model number is 852. Thus, I enter the code as instructed, and receive an error message, which follows me with every future attempt I make with other codes just in case: "Connection problem or invalid MMI code"

Source for the MMI code information: The article is called "How to disable KnockON (double tap to wake) on the LG G3 and other LG Android phones" but I cannot link it in my post.

Now, I've asked LG for their customer service person to help me out. After a series of live chats and calls, mostly summing up to "Hard Reset" a specialist told me that the code which I found online is wrong for my phone. Because my provider is Canadian, "3845" is not how my code is supposed to begin. Therefore I have to ask my provider, Virgin Mobile, to give me their MMI code. Virgin leads has their own agent then explain to me that they don't have any MMI codes, that this is a matter for the Manufacturer to handle. Therefore I was just led in a loop. Which one is really supposed to have this number in one of their documents somewhere? I'd imagine somebody made the system and determined how these phones are preset before customer use, including these, and that the rules can be found somewhere. This is irrelevant, as it appears I will never know.

Among the other solutions I've tried through research and suggestions by the help desk agents include:

-Going to the Mobile Networks submenu and making sure that my provider's network is properly selected (after all, the first part of the error message says "Connection problem...")

-Using a comma or a plus sign in various places when dialing in order to use their supposed ability to force the MMI code to go through by ignoring the error message (the comma never had any effect, and the plus sign failed with a disconnecting call)

-Restarting my phone

-Inputting the code while in Safe Mode

One possible solution that failed was accessing the hidden "Info" menu in order to enable SMS Over IMS (VoLTE). This was suggested as a solution, for reasons unknown to me, but I could not even attempt it because a message popped up when I tried to access that section of the Info menu, clearly stating that my phone wasn't permitted to go there. This hints that maybe my Service Menu is disabled too, but can't be assumed with absolute confidence.

As far as I am aware, these are all the steps I've taken to resolve this issue, and all the necessary context behind it. If you stop by to help, I thank you very much for your time and effort.