[Android Central Question]

The phone is rooted with King Root. Its useless to me as a Virgin Mobile
phone. Is there a way to change the firmware for GSM?
If not, can I update the firmware to something newer with better bluetooth
support.

Thanks,
ken

[Mooncatt]

That phone is no longer supported by Samsung, so you won't find any official updates. Your only option is to look for third party ROMs, but even that is not a guarantee. You'll need to find one specifically developed for your device (even down to the carrier version if that applies to you). If you do find that, it'll likely be rather old itself and it may not even have the specific updates you're looking for. Assuming you do find a ROM you want, you then need to research how to root your phone and install it. It's not as simple as installing a regular official update that downloads and does everything for you.

[Rukbat]

You might try https://www.sammobile.com/firmwares/. (Since we don't know the model/country, we can't look it up for you, but they might have it.)

The difference between CDMA and GSM isn't just the firmware, it's a different motherboard too.