If your mobile data and/or Wi-Fi aren’t working after flashing a custom ROM, the answer is here — keep reading…

In 2013 I renewed my T-mobile contract and got a new Samsung Galaxy S3.

The phone was great (still runs very well), but came loaded with Android 4.1.

Why I Wanted to Install a Custom ROM on My Galaxy S3

T-mobile and some other providers eventually did let their customers upgrade to Jelly Bean v. 4.3, but the problem was that I had rooted my Galaxy S3 (in order to remove annoying apps that came with the phone such as Visual Voicemail [update: Visual Voicemail has improved and is not so annoying any more, so I have not rooted my new Galaxy Note 5…at least not yet…], which could not be uninstalled the normal way) a while before they released this update, which made me unable to receive updates such as this.

Lately, I’ve found myself smitten with desire to get a smartwatch of some sort to pair with phone. The problem: most smartwatches require Jelly Bean 4.3 or higher.

I could either buy a new phone or upgrade the OS on my Galaxy S3.

The S3 worked fine, so I saw no need to drop a load of cash on a new phone sporting marginal improvements.

Thus was born my quest to upgrade my Galaxy S3 and install the latest version (update: at the time) of the Android OS, 4.4 KitKat.

Now, if you’ve never done something like this before and try to go to the Internet for step by step instructions, you may be disappointed. Much of the information out there can have one or more of the following flaws: out-datedness, incomplete, confusing, or flat out wrong. Plus, the information is fragmented across many different sites and forums. Because of this, one can easily spend HOURS sifting through crap ad-infested search results or info that is simply irrelevant or leads nowhere. God bless the Internet.

With that said, you know the landscape of technology is one that changes fast and often. As things evolve, I’ll try to keep up but please remember that I have no control over most of these changes and cannot guarantee that this info will remain accurate or complete forever.

Oh, and it’s easy to brick your phone if you do something wrong, too.

So I’m going to lay out the steps below.

How to Install a Custom ROM on Your Galaxy Phone

Step 1: Root your phone. Directions on how to do that could fill a blog post and a half on their own, so I’ll leave you guys to the untamed territory known as the Internet for info on how to do this (at least for now, perhaps a future post will cover rooting). But before you start, make sure your contacts, pictures, etc are backed up.

Step 2: The Galaxy S3 has a slot for a micro SD card under the battery. This can come in handy for storing backups of your whole phone (discussed next), and provides extra storage for the phone.

Step 3: Install Clockwork Mod Recovery on your phone so you can back up the entire phone. You’ll use this to restore the phone if something goes wrong or you decide you don’t like KitKat and want to revert back to whatever version of Android you’re currently running.

You’ll also need this to flash the new ROM.

You can install this by searching for “ROM Manager” in the Google Play store. Also, this site has some useful info pertaining to this app.

Step 4: Once ROM Manager is installed, make a back up of your phone (preferably on the micro SD card). Do this by holding the volume-up button and the button on the opposite side of the volume button while turning the phone on (on some versions, you may need to hold volume-up, side button, and main button by charging port all at once while turning phone on).

Use the volume keys to scroll and the button by the charging port to select options.

Scroll down to “backup and restore” and select.

 

Then either “backup to /sdcard” which stores the backup on your phone or pick “backup to /storage/sdcard1” which backs up to the micro SD card (if installed).

The backup may take a few minutes. After it’s done, reboot the phone.

Step 5: Just for good measure, I’d take that backup and copy it to a desktop or laptop computer for safe keeping. Install the tether (a.k.a. ADB) drivers on your computer of choice. You can get them here.

Once the drivers are installed, plug your phone into a free USB port with a micro USB cable. You may need to enable USB debugging by going to the developer options menu item.

If you’ve backed up to a micro SD card, you should be able to drag and drop the backup to your PC. If not, you’ll need to use ROM Manager on your phone to download it to your PC. Make sure the phone is on the same network as the PC you’re saving the backup to (via Wi-Fi) then type the IP address given by the app in your browser.

Step 6: This part is optional for some, mandatory for others as without it some people may not be able to use mobile data and/or Wi-Fi after flashing the new ROM. The old saying goes if it ain’t broke don’t fix it and that’s the exact philosophy I’d use if I were you. Installing the wrong radio firmware (baseband) for your phone can make it an attractive paper-weight.

If you find that mobile data or Wi-Fi does not work after flashing a new ROM to your Galaxy S3 (or any other phone for that matter), you can just revert back to the stock ROM (using ROM Manager), then update the firmware for the phone’s radio (again, using ROM manager). Do NOT install the wrong radio firmware! Here is a link to the radio firmware for a handful of T-Mobile Galaxy S3 phone models, including the SGH-T999. If you have a different phone or different carrier, you will have to search for the baseband modem software, or contact the company and ask them for it of you can’t find it.

Use ROM Manager to install the new modem software by placing the file on your micro SD card, booting into recovery mode, picking “install zip” from the main menu, then choosing the appropriate file.

Step 7: Download a custom ROM of your choice. You can pick from several different ROMS for just about any phone by going here. I put CyanogenMod on mine and it seems to work well. You may want another, such as Pac Man ROM. There are lots of ROMS, do some research first to see which one has the features you want, is stable, and is highly rated.

Again, put the file on your phone somewhere, boot into recovery mode, pick “install zip,” find the file and install it. Reboot.

You may also want to install the Google apps package next if you plan to reconnect to Google services.

If all goes well you’ll have what may appear to be a completely new phone with Android KitKat 4.4. Make sure your battery is charged at least 75% or the phone is plugged into a power source when flashing anything!

If you find that mobile data and/or Wi-Fi are not working after the flashing, refer to step 6.

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