HTC One (m8) upgrading from lollipop to marshmallow and getting error 155


    Hi all, I recently bought a HTC One (m8) with a stock T-Mobile OS version 4.20.531.5 (lollipop?) and downloaded marshmallow 6.0 for T-Mobile  from to upgrade OS.  I also downloaded the HTC sync manager and followed all instructions to upgrade phone but I keep getting the ERROR 155.  I have tried fastbooting as well, but still gives me same error.  Can anyone help me?


    Thanks in advance.

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