I'm in need of help for my phone due to a mistake that I did.
First I have to give you some context. Here where I live (Puerto Rico), there's no B26 and B41 is extremely limited to a very few selected areas in the island. The only choice in my area was B25 which is severely congested. So congested that in a good day, I only see 0.40 Mbps download and ~0.10 Mbps upload. A few months ago, Sprint and Open Mobile (a local CDMA carrier on the island) did a joint venture merging their networks. As a results, on a lucky day, my phone will connect to Open Mobile's blazing fast B13 in my area (upwards 10 Mbps).
This B13 Open Mobile thingy is working natively (no roaming and no extended network) fine but my phone prefers B25 which is from Sprint and is congested.
Now the good part. I was looking for a way to force B13 or at least to change this band to a higher priority in my phone (Moto X4) so it would connect to B13 instead of B25. To my surprise, supposedly I found a method to do this just like with Samsung phones. By pressing *#*#DATA#*#*, a menu appeared with multiple options, including LTE settings. In this menu, there was an area to assign priorities to the available bands which by default, where B13 (fourth), B25 (first), B26 (second) and B41 (third). To change these priorities, you had to input a password which conveniently was 000000. As a very curious person, I change the priority values to the following: B13 (first), B25 (second), B26 (fourth) and B41 (third), pressed the done button and the exit the menu.
Following that, I went to SCP to see if there was any change but SCP reported that it was still connected to B25. Perhaps the phone needed a reboot to implement the new LTE priorities.
As soon as the phone rebooted, I was greeted with an invalid SIM message and no signal (no LTE, no 3G, no call, nada). The SprinDM service did not work, wifi was disconnecting after every "invalid SIM" message (perhaps the wifi radio was affected?). After doing a factory reset, the same message was all over again.
A trip to a local Sprint shop was wasted. One of the employees (regular employee, there was no technician at this store) managed to get the SprintDM service running and was successful in getting the "config file" option in the service but still, calls and LTE was not working (no signal). He even use a built in app called CQATest which was new to me. According to him, the app reported that the phone was "seeing" the Sprint network but that perhaps there was something wrong with the phone that was beyond his knowledge.
A call to Sprint customer service yielded not results. The did some "refresh at their end" and had to wait 10 minutes before turning on the phone again but still, the phone is unable to connect to Sprint.
The funny part...
As this phone is (GSM/CDMA), I proceeded to insert a working T-Mobile SIM and guess what, I got full LTE and everything with T-Mobile. Full VoLTE, calls, LTE, text messages, wifi, everything work any other SIM except with a Sprint SIM. If insert my Sprint SIM, my phone behavior changes for the bad.
To wrap this up.
Any idea on how to fix this? I tried to change the priority values to the default ones multiple times and nothing. Multiple hard resets and nothing. I'm out of ideas.