[One (M8) Q&A, Help & Troubleshooting] Sneakyghost:
The hardware of the Verizon M8 (or M7 or M9 for that matter) is not any different than the international versions. Same goes for Sprint. They all are 100% identical.

The difference is: the Radio/Modem part of the SoC has its own firmware and is locked to a set of frequencies depending on who ordered the Phone. For Sprint, its their set of CDMA as well as some LTE and some GSM frequencies ("Sprint World Phone"). For Verizon, its a set of CDMA and LTE and possibly some GSM frequencies. I don't know who has exactly which bands unlocked.

However, this lock is quite different from the Security Lock we know as "S-ON" or "S-OFF" - its independent and normally cannot be changed. However, there is a set of tools and guides to fully unlock all frequencies in that Qualcomm chip. I don't follow those threads but the last time I checked, they had not succeeded in making these low level radio changes stick past a reboot.

The main difference however is a variation in the partition layout of the NAND. The NAND chip is partitioned in 47 partitions on GSM and Sprint, but both having slightly different orders of the partitions, and Verizon has 48 partitions, with again slightly different orders. I have this partition list linked in my main thread - look it up there if you are interested.

So, this means, worst case scenario: flash a GSM ROM to your Verizon device and have it not boot and wrong data in the wrong places. You will need a RUU to fix that.

Flash GSM Firmware to your Verizon device and this might get worse. Depending on the order sequence of the partitions and the phone we are talking about, the worst case could be a brick.But usually, all 3 main variants have identical boot-critical partitions and those are also usually in the same places. Chances to brick are very little. However, I have seen it happen. So the chance is >0.

As long as it is not a brick, run a RUU and you will, again, be fine.

Since these differences are very difficult to work around, it does not make ANY sense whatsoever to even consider converting a CDMA phone to GSM. Nobody has yet fully managed to do that.

Especially because there is one absolutely critical ingredient missing to achieve a full conversion: We have no means to repartition the NAND.

Back on the HD2, I was able to repartition the NAND by means of directly talking to the chip with TTY commands, but that seems no longer possible on current devices. The only way I can think of would be to use the same Qualcomm tools the people use to do the radio unlocking, to try and abuse those to repartition the NAND. But that takes way more skills than I call my own.

---------- Post added at 07:08 PM ---------- Previous post was at 07:02 PM ----------

A kernel holds a ton of links to all sorts of partitions. Since I explained above how the partition table differs across devices, a Kernel would need to take those different pathes into account.

Then, the Kernel will need to be meant to work with CDMA files in the ROM.

Then, the ROM will need to actually HAVE those CDMA files (means the Dev of the ROM needs to have made it so it can work with CDMA). If the ROM says "GSM Only" it won't be working on a Verizon phone by just changing the kernel. It might boot but you will find a lot of features broken.

Long story short: check for ROM's that explicitly state "For Verizon". It is quite possible to make WWE ROM's work on VZW but its a ton of work and speaking from Team Venom's behind-the-scenes perspective, converting a GSM ROM to VZW is what makes our devs often enough wanting to quit it alltogether. Its a pain in your backside and not as easy as it might appear.