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.
Use a known-working, MFi-certified Apple cable and wall adapter. Cheap, non-certified cables often damage the internal charging IC. iphone-6-no-power-solution-100-working
If the battery is completely drained, the phone may not respond immediately. Go to product viewer dialog for this item