Monday, August 1, 2016

What phone PCB version do I have / Can I downgrade from marshmellow if I have it?

This is a summary of what I know about the new phone variant that can't be downgraded. It's a summary from another thread.

Phones with a model "K" obey the known to be blown bootloader "version" qfuse on 47A, preventing a downgrade. They also refuse to flash TOTs from any version. You should be able to still downgrade using dd as shown here but only if you have NEVER touched 46/47A Marshmellow stock firmware. That will blow the bootloader version qfuse and forever lock you out of anything non-marshmellow, including 35B!

Old boards (non K PCB revision "1" boards) do not obey this qfuse and can do whatever the heck they want. "K" models must never flash marshmellow if you want any hope at a downgrade, and even then, the TOT method does not work until you follow the guide above using dd.

This has proven true with me on several phones. There is a small yet notable exception to all this, however. Some models ship with the modified PCB (that obeys blown qfuses and fights downgrades) without the external "K" on the model number. This means the only SUREFIRE way to tell is to look on your PCB for the small "revision" code in parenthesis at the end of the model. It will be in gold circuit-trace style font, and look like this "VS985 PCB v1.0 (2)." The "(2)" means it obeys qfuses, a "(1)" means it is an original model and does not.

I have tested this across a bulkpack of 10 "defective" LG G3's I have sucessfully brought back to life from ebay. It seems a pretty solid foundation for my claims.

I attatched some photos to help with identification:

Attached Thumbnails
Click image for larger version Name: PCB.jpg Views: N/A Size: 212.8 KB ID: 3830621   Click image for larger version Name: MODEL.jpg Views: N/A Size: 245.4 KB ID: 3830622  


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