Often, the phone is powered on but "frozen" with a black screen. A force restart can jumpstart the system.
Go to product viewer dialog for this item. that won't power on, start with simple software and external hardware resets before moving to advanced board-level repairs. iphone-6-no-power-solution-100-working
Use a known-working, MFi-certified Apple cable and wall adapter. Cheap, non-certified cables often damage the internal charging IC. Often, the phone is powered on but "frozen"
Keep holding both for at least 10–15 seconds until the Apple logo appears. 2. Check Charging Components the phone may not respond immediately.
If the battery is completely drained, the phone may not respond immediately.