The Phantom V Fold relies on a magnetic sensor to know when it is open or closed. If the phone thinks it is closed (even when it is open), it will keep the inner screen black. Conversely, if it thinks it is open, the cover screen will stay black.

Lithium-ion batteries have a protection circuit. If the battery is drained to 0%, the phone won't turn on immediately when you plug it in. It needs to trickle-charge to a safe voltage before the screen will light up.

Additionally, check your screen protector. If you have applied a third-party UV screen protector on the inner screen, the liquid adhesive may have leaked into the proximity sensor area near the