[Samsung Galaxy Core Prime Guides, News, & Discussi] bogarty:
Before I get into it, let me just start by saying that I have spoken to MetroPCS and they have confirmed that this phone was specifically set up to use the "Device Unlock" app ONLY, which means that there are no unlock codes or any other procedures(not Chimera or any other one) that will unlock this device.

For those of you who don't know too, you MUST wait until after 90 days of service with MetroPCS on this device before you can unlock it. If you can't wait the 90 days, however, because you're going to travel or because you live outside of the country, I've been told that there is one other way to unlock this device through a third party service that works with MetroPCS and helps you unlock through the app as well, though it is more like "IMEI whitelisting" than an official unlock like you get with MetroPCS and you also have to pay.

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Anyhow, now to get down to it. Here is the information on what you must do.

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1) Wait The 90 Days - Actually, you should know first that MetroPCS does not count the extra day in the months with 31 days as part of the 90.[/B] In other words, if you bought your phone on the 10th of one month say, you have to wait for the 10th to come around again 3 months later.

2) Try Unlocking The Device - Go to the "Device Unlock" app in your app tray and try clicking on the "Permanent Unlock" button to see if it just works for you right away. I was not so lucky myself, but I've been told that it does simply just unlock for some people. If it did unlock that easily for you, then congratulations. That's it. You're done. :)

(NOTE: Make sure that it is actually unlocked though. See the attached images and step #4 below.)

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If it still isn't unlocked after steps 1 & 2, then please read on...

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3) Call MetroPCS - If it won't unlock, then MetroPCS may have placed a server side lock on your account for whatever reason. In this case, you will need to just call Metro and request that they go into their system and set "Allow Unlock" to "ON" for your device. It only takes them a few seconds to do, but the first 3 people I called some days before didn't even mention or seem to know that their system had this feature, so you have to ask. After they did this for me I was able to successfully unlock the device using the app.

4) Double Check That Your Device Is Actually Unlocked - After unlocking the device the app says that the "Device Is Permanently Unlocked"[/B] and prompts you to reboot. After rebooting though I recommend that you open the "Device Unlock" app again and make sure that it no longer contains the reboot menu(shown in the first picture attached below). If it keeps saying to reboot because the settings are not yet applied, then you are still not unlocked. You want it to look like the second picture I attached below and NOT the first. Try rebooting a few more times to see if this problem fixes itself.

(NOTE: If you still can't unlock fully and have rooted the device and have TWRP and the Xposed framework installed, then you can also try installing an Xposed module called "Good For Enterprise Disable Root Check" to see if that allows the unlock settings to apply. Otherwise just call Metro again to make sure you are unlocked.)

Anyhow, I sincerely hope this information helps you guys in unlocking your device! :)