XPS 8920, Boot problem

Computer config:

Dell XPS 8920 Desktop

Windows 10 Home edition

Monitor: HP 22.5"

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Hi, 

I wanted to install a dual boot Linux Mint / Windows 10 on my computer. However, I never succeeded in booting from the USB stick because my monitor was off, and turned on only at the lock screen of Windows 10 (i.e. when the computer started, I had no Dell logo, no Windows loading, the screen was just off). When I checked the display parameter in Window, I realized that there was a phantom monitor (see here), which was probably set as the default one upon starting the computer... I tried to update the driver but it didn't work, so I followed a terribly bad advice to disable the Intel HD display adapter in the device manager (note that there were two display adapters, Radeon and Intel HD, as my graphic card is an AMD Radeon I thought that the Intel HD was obsolete). Immediately, my screen turned off.

I then tried to re-initialize the BIOS by unplugging the computer, removing for one minute the motherboard battery and then replugging the computer (see here). This operation didn't work and unfortunately, worsened the things because now my computer starts for one minute (with the display still off) and then shut down. What worries me is that I have not even a LED light on the keyboard. I tried to repeat that operation 3 times, and carefully verified that all the hardware was plugged correctly, but still the same problem. 

Any solutions would be really appreciated,

Best regards

Raphaël