Course: CompTIA Certified A+ Training (Core 1 and Core 2) (TGS-2024048317)
Topic 05: Hardware and Network Troubleshooting — Core 1, 28% of Core 1
Exam objective: Diagnose mobile device hardware faults including battery, charging, screen, digitizer, port and overheating problems, applying the correct safety response (Core 1 objective 5.5).
Mobile faults carry a safety dimension that desktop faults do not: a swollen lithium battery is a fire and chemical hazard. You build the diagnostic map and, for each fault, record both the technical response and the safety response.
A mobile fault diagnostic map with a technical and a safety response for each of ten faults.
Mobile device, charging cables, battery health screens, device settings
- Disconnect mains power and hold the power button for 15 seconds before working inside any machine.
- Wear an anti-static strap connected to an earthed point; hold boards and cards by their edges.
- Never open a power supply unit or a CRT monitor — both retain a lethal charge after being unplugged.
- Never puncture, compress or charge a swollen lithium battery; isolate it and follow hazardous disposal procedure.
- Record the safety rule that governs this entire lab: a swollen battery must never be punctured, compressed or charged. Power the device down, isolate it from flammable material and follow the organisation's hazardous disposal procedure.
- Check battery health from the device's own settings, recording the maximum capacity percentage and the cycle count where the operating system exposes them.
- Diagnose poor battery life by separating its causes: a genuinely degraded battery, background applications, a weak cellular signal forcing the radio to full transmit power, or high screen brightness.
- Diagnose a swollen battery from its physical signs — a lifting screen, a bulging back cover or a device that no longer sits flat — and apply the safety response immediately.
- Diagnose improper or intermittent charging by testing in a fixed order: substitute the cable, substitute the charger, inspect the port for lint and damage, then suspect the battery.
- Record that a charging port packed with pocket lint is extremely common and is cleared with a wooden or plastic pick on a powered-off device — never a metal tool.
- Diagnose a broken screen by distinguishing cracked glass with a working display, a working digitizer with a dead display, and a working display with a dead digitizer.
- Diagnose digitizer failure as touch that is unresponsive, offset from where you press, or registering phantom touches, while the image remains perfect.
- Diagnose overheating from its causes: sustained high load, a faulty charging circuit, an ambient heat source, or a failing battery — and record that persistent overheating with a swollen battery is an immediate safety stop.
- Diagnose liquid damage, record that the device must be powered off and not charged, and note that visible corrosion means board-level damage requiring specialist repair.
- Diagnose physically damaged ports and record the repair options in order of cost: port replacement by a specialist, board replacement, or device replacement.
- Complete the map with poor or no connectivity, cursor drift requiring touch recalibration, and malware symptoms, giving a technical and a safety response for each.
Every fault in your map has both a technical and a safety response; the swollen battery entry forbids puncturing, compressing and charging; and the charging diagnosis substitutes cable and charger before the battery is suspected.
| Symptom | What to check |
|---|---|
| A command returns "command not found" | Re-run the apt-get install step at the start of the lab — the playground starts with a minimal package set. |
| The Killercoda terminal has reset | The playground times out when idle. Reopen it and re-run the setup commands from step 1. |
| A browser tool will not load | Check the URL against labs/tools.md. All four tools run entirely client-side and need no login. |
| Output differs from the guide | Record what you actually observed — your environment differs from the reference, and explaining the difference is part of the exercise. |
- State the exam objective this lab maps to, in your own words.
- Which single step in this lab would you perform first on a real support call, and why?
- What evidence would you attach to a support ticket to show this work was completed correctly?
- Name one thing that would make this procedure fail, and how you would recognise it.
Complete worksheet.md as you work through this lab and keep it — the Practical Performance assessment mirrors these tasks.