Can't get to fastboot. nor twrp nor OS - Xiaomi mi 5X/A1 I'm having a problem with my Xiaomi mi 5X and i wondered if someone on this forum could help me solve it.
As i said, i have a Xiaomi mi 5X but i changed its firmware and OS to the one of Mi A1 (Android One).
Today I was trying to install on my device the GCam app, with the tool Mi A1 GCam.
After I clicked the "Enable HAL3, EIS and install" the phone went dark. Now i can't boot into the OS, nor the twrp nor to the fastboot mode. When i try to do it i have to hold down the power button and corresponding volume key for several seconds and the Android One boot screen appears but just in a flash, and goes dark again. 
Can any of you help me, please?
Thank you
Have you tried using adb? 

If you haven't got it already, download the SDK tools for windows from https://developer.android.com/studio/ under the "Command line tools only" section, and unzip it where you want.

Once you've done that, open a command prompt in the platform-tools folder within the SDK directory. The command

adp devices


will tell you that your device is connected. Then you can try

adp reboot recovery


If that doesn't work, install the universal adp driver and try again.