There is no ribbon connecting the buttons with MB. Without the MB back plate securing it the buttons are defunctGuys this is my procedure to turn on the phone:
I can make it turn on Android after messing with the battery and sub-board cables but this is just a workahound, trying to turn it on normally through the power button always makes it turn on in edl mode
But opening the device voids the warranty, so anyone who has access to a repair center is better off asking for the warranty
What to do:
1. Disconnect the battery cable and the secondary board cable.
2. Connect charger.
3. Hold the power button.
4. Connect the secondary board cable and quickly connect the battery cable.
5. Release the power button when the device vibrates.
It doesn't always work the first time, you may need several tries to get it