[Q] Trouble to upgrade bootloader from MK5 to MJB to NE4

I've been serching for an answer for a while and can't seem to find a proper one that makes sure that I won't brick my phone. I've been flashing roms since 2011 and know pretty much the drill but lately I've been flashing at a couple months interval CM11 m builds and since I don't follow the threads like I used to, I feel like I'm missing out on how to do the right procedure.

So this is my phone:

Rogers i747 SG3
Cm11 4.4.4
Bootloader: I747MVLUEMK5
Baseband: I747MUMUEND3

I've installed these about a month and a half ago and since I've lost LTE networking but I didn't care to try to fix since I don't use it that much and left it like that.

This morning, I tried flashing MJB bootloader and modem zip in recovery but it gives me the classic error 7

Any Idea how to get out of this impasse? I've been searching all morning and can't find what I'm looking for...

audit13 said:

What recovery are you using? Is it up to date?

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I use Clockworkmod recovery 6.0.4.7 The latest version and Its an at&t i747 phone but with Rogers(same thing).

Is there other basebands or bootloaders I can maybe update with?

Cool yeah it is a i747m you're right.

Once I install the latest (canadian) firmware, does that give me the possibility to flash mjb and the Ne4 to have access to the latest cm roms without any trouble? Not sure if i understand everything here...

audit13 said:

Do not flash any firmware not specifically designed for the i747m. The mjb bootloader is for the i747 and flashing that on your phone would probably brick it.

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Well thanks for the link. I updated my firmware and played with the apn and now the LTE works again and hitting an 80 mb download... pretty crazy.

So are you saying that a i747m would not be able to flash cm12(lollipop) which states in the nightly thread that it needs a NE4 bootloader/modem?!