Yeah, the only way to recover the CBHC Format Brick is via HardMod.
Its not hard to do, but you do need experience with Surface Mount Soldering, and cutting small traces on PCB's.
There might be some people on here willing to hardmod your WiiU and recover your console for you, for a small price plus shipping costs. But im pretty sure you still need at least the OTP.bin Backup for the bricked console. The OTP.bin is used to decrypt and re-encrypt the nand (and other files that need to be decrypted/re-encrypted).
There may even be computer repair shops near you that offer this kind of service too. You should try to find some shops near you and give them a call, and ask them.