[Samsung Galaxy A50 Questions & Answers] L!V3_4_XC3SS:
That second prompt when you put in the US Mobile Sim is deceiving - that's what we wanted... 000000 or 123456 probably would have done it - I think it's the same as the SPC (Service Programming Code) there is almost no research in this area that I've been able to find outside of my own, and I'm limited in what I can do because I'm not in possession of an A-50 with the problem so if we get this you're helping others by bearing with me.

Of course the obvious thing that could be done is to just fflash the multi-rom with the US Mobile CSC included, like we did above, but that still won't unlock the APN - it's just likey to populate it with the correct values from the carrier. To do that properly would wipe your son's A50

So let's try to unlock this as it's the first best choice...

Go get this and tell me what it says on the status of your sim - should be nework unlocked but it may show the secondary protection.

Network/WIFI Info & Sim Query - Apps on Google Play

Get all details of your Mobile Network, WiFi & Sim Information.

play.google.com

This should give you a good shortcut into the APN settings to check and see if you can 1. reset to default if that will give you connectivity, and 2. Add an APN when we unlock the phone

APN Settings Shortcut - Apps on Google Play

1 Tap to open APN settings. This is shortcut app. Minimum ad. No Permission.

play.google.com

As there are a lot of folks who didn't find this obscure thread who will be happy if we figure it out. Let's try the easy stuff first and then I'll get into the ADB command line stuff and tools and codes if we can't get any love with this . So first let's try to clear the prompt "This user not allowerd to change APN Settinggs, etc.::

Make sure that you are in the range of a known Wifi Network and follow the next steps:

Turn on Wifi and wait for your phone to connect to it

While connected to the Wifi Network, reboot the phone

As soon as the device restarts it will automatically connect to the previous Wifi network

Go to APN settings following the above-mentioned path and check if you are now able to view/edit

OR

Turn Wifi ON

Go to Settings -> Mobile Networks -> Network Operators

A search will be executed and afterward, the list will be populated with one or more Network Operators

Choose the Network Provider from where you bought the SIM card

Go to Access Point Names and add the new APN

Save the data and done.

OR

With Wifi on pull your sim and reboot the phone - once booted reinsert your sim and see if it asks for a code....

Try 000000, if that doesnt' work try 123456

If none of that works We will make the attempt to access the APN settings using ADB which is the command line Android Debug Bridge... if you don't have it installed there are guides on how to do so all over XDA, the ADB shell runs not quite as root but at a much higher privilege than the normal user account, so we'll try it from there if none of those work. I 'm sorry I don't have the device or I'd come back with a definitive how to - but for now we'll have to go trial and error, guarantee we'll figure it out, it's I know Samsung devices in general and they're not that different. Many roads my friend.

ADB

Service Mode Codes

My toolbox has utilities that will get it 4 certain if need be.

L4XS