About the Custom Firmware Method
The CFW (Custom Firmware) iCloud Bypass is currently not possible due to the fact that an iBOOT, LLB, or BOOTROM exploit is needed to push the CFW file.
Normally, Apple signs the files with their own keys, and the device will check whether the iPSW's signatures mach the ones that the file should have. If the signatures are different, the device will know that the iPSW has been tampered with, and will trigger the ERROR 14 or the ASR ERROR 110 during the restore.
The Error 14 can't easily be fixed. Unless you have an iBoot, LLB or BOOTROM exploit to be able to disable the signature checks on the device, you can't push the firmware, and therefore, creating a CFW for iCloud Bypass is no longer a feasible idea until an exploit for such a low level component will exist publicly.
There are BOOTROM exploits available, and they have been used in the past for CFWs on iOS, but they are for older devices like iPhone 4, iPhone 3GS and so on, which means you can't use them on anything newer than that. iOS Kernel Exploits are released more commonly as they are built easier, but they are not useful in this context. During the restore, a Kernel exploit is useless. Components like iBoot, and the BOOTROM are very low level. For iBoot, there are exploits compatible with newer devices (iPhone 5, 5C and possibly even newer), but they are kept unpublished to avoid Apple patching them. BOOTROM exploits can't be patched in software, but the BOOTROM code is so small, it is virtually impossible nowadays to find a vulnerability in it as the attack surface is too small and there is no way to see what you are doing plus, Apple has fuzzed the hell out of the BOOTROM to avoid repeating the limera1n situation. Limera1n is a very powerful BOOTROM exploit created by George Hotz (geohot) for A4 devices (iPhone 4 and so on), it is unfortunately patched on iPhone 4S (A5).
To learn more about this, please check out our CFW iCloud Bypass F.A.Q. Page!