Charging
Common charging-port failures and how to diagnose them fast
6 min readUpdated Aug 11, 2026
"It won't charge" is one of the most common walk-in complaints and one of the easiest to misdiagnose. Replacing the port flex on a board-level fault costs you the part, the labor and the customer's confidence.
Work the list below in order. Most tickets resolve before step four.
Start with the cheapest causes
The majority of charging complaints are mechanical or environmental, not electrical.
- Compacted lint: a pocket-carried phone accumulates a felt puck at the base of the port. The cable feels like it seats but never bottoms out. Clean with a wooden or nylon pick, never metal.
- Customer's cable and brick: test with a known-good cable and charger before anything else.
- Bent or recessed pins on Lightning; a splayed centre tongue on USB-C. Inspect under magnification.
- Liquid corrosion: green-blue residue on the port contacts, often with matching corrosion on the flex.
Distinguishing port failure from board failure
The pattern of symptoms tells you where the fault lives. This is the fastest way to decide whether to order a flex.
| Symptom | Most likely cause |
|---|---|
| Charges only at a certain cable angle | Worn/damaged port — replace the flex |
| No charge at all, no charging icon, device cold | Port, battery flex or charging IC — test in order |
| Charges but no data / no PC recognition | Port data pins or corrosion on the flex |
| Charges very slowly on every charger | Port contact resistance or a degraded cell |
| Gets hot at the shield near the charge IC | Board-level fault — do not just swap the port |
| Accessory-not-supported errors | Contaminated port or a counterfeit flex |
USB-C specifics
USB-C ports fail differently than Lightning. The centre tongue carries the contacts on both faces, so a sideways yank splays it and creates intermittent contact on one orientation only. If the phone charges when the cable is flipped but not otherwise, the tongue or one contact row is damaged.
USB-C also negotiates power over the CC pins. Corrosion there produces the classic "charges at 5W on a 45W charger" complaint even though everything else looks fine.
Install notes that prevent repeat visits
A charging port flex usually runs under the battery and shares the assembly with the microphones and antenna lines, so a sloppy install produces symptoms that look unrelated to charging.
- Route the flex flat under the battery adhesive — a fold creates a pressure point that fails within weeks.
- Reconnect the antenna and mic contacts fully or the customer returns for "nobody can hear me".
- Replace the port gasket or the water-resistance seal when the model has one.
- Test charge rate, data transfer, both microphones and speakerphone before closing.