Direct answer
For the Dell XPS 16 9640, one key/region, accessibility settings, debris/liquid, external devices and hardware should be separated. First, test in firmware/login and a simple text field with external devices removed.
What this covers
- Dell XPS 16 9640 (XPS 16 9640)
- Dell PC family; use the service tag for exact BIOS, drivers, ports and warranty configuration.
- The specific fault this record addresses: keyboard or trackpad is not working correctly
What it does not cover
- ×The same symptom on a different Dell product line, which has its own record and its own cited source
- ×An on-screen error code whose meaning has not been checked against this exact model's manual
- ×Live electrical, gas, sealed-system, internal battery-cell or structural repair — a technician boundary, not a self-service step
Differential
What actually causes this, and how to tell them apart
These are ordered by how often each one is the answer, not by how easy it is to try. The point of the middle column is that two causes producing the same headline symptom rarely produce the same detail — that detail is what tells you which one you have before you change anything.
- 1
The keyboard layout or language is wrong
What separates it Keys type the wrong characters, particularly quotes, @ and # symbols, rather than not working.
How to confirm Wrong characters means the hardware is fine and the layout is set to a different region. This is a settings change, not a repair.
- 2
An accessibility setting is altering input
What separates it Repeated keys are ignored, keys need holding, or the pointer moves strangely.
How to confirm Sticky Keys, Filter Keys, Slow Keys and Mouse Keys all change input behaviour and are easily enabled by accident through keyboard shortcuts.
- 3
Debris under specific keys
What separates it Individual keys are unresponsive or feel different, while the rest work normally.
How to confirm Individual dead keys point at debris or a failed switch rather than anything system-wide.
- 4
The trackpad is disabled or being disabled by a connected mouse
What separates it The trackpad does nothing, often with an external mouse connected.
How to confirm Many machines have a setting to disable the trackpad automatically when a mouse is connected, and a keyboard shortcut to toggle it that is easy to press by accident.
- 5
Liquid has been spilled
What separates it Multiple keys failing at once, or keys behaving erratically, after any spill.
How to confirm This is the one input problem that needs immediate action rather than diagnosis — see escalation.
- 6
The system has stopped responding rather than the input device failing
What separates it Neither keyboard nor trackpad responds, and nothing else on screen updates either.
How to confirm Check whether the machine is responsive at all — a frozen system looks exactly like failed input.
Before you touch a setting
Record this first — changing settings destroys the evidence
Every item below stops existing the moment a reset, re-pair or settings change is made. Written down first, they are what separates the causes above; recovered afterwards, they are guesswork.
- Whether the whole device is dead, some keys are dead, or input is wrong — these are three different problems.
- Whether an external keyboard works, which separates the hardware from the system.
- Whether anything has been spilled on it, at any point.
- Whether an external mouse is connected, which can disable the trackpad by design.
Determine which of the three groups this falls into
ReversibleWhole device dead, some keys dead, or input misinterpreted — each points somewhere completely different.
Check the keyboard layout and language setting
ReversibleKeys typing the wrong characters means the hardware is fine and the layout is wrong.
Check accessibility settings for Sticky, Filter or Slow Keys
ReversibleAll are enabled by keyboard shortcuts and are commonly triggered by accident.
Connect an external keyboard and mouse
ReversibleIf those work normally, the system is fine and the fault is in the built-in hardware.
Check whether a connected mouse is disabling the trackpad
ReversibleMany machines do this by design, and there is usually a shortcut key that toggles it.
Model-specific
What is true of this model and not of its siblings
Generic advice for the product line fails here. Each item below is a property of this specific model family that changes which of the steps above apply to you.
- Model scope
- XPS 16 9640. Dell PC family; use the service tag for exact BIOS, drivers, ports and warranty configuration.
- Tier — premium 16-inch creator (Windows 11)
- A large premium 16-inch Windows 11 laptop with a strong discrete NVIDIA GPU and an OLED option — a creator/light-gaming machine. Minimalist keyboard/touch row design.
- Dual graphics + thermals
- Integrated + discrete GPU with Windows switching; force demanding apps to the NVIDIA GPU if they run slowly. As a powerful thin machine it runs its fans hard under load, which is normal.
- Ports — USB-C/Thunderbolt
- USB-C/Thunderbolt (plus microSD); use a dock/adapter for legacy ports.
- Power path
- Internal or removable battery. Every capability that costs current — night vision, higher stream quality, longer recordings, frequent events — is paid for in runtime, so a change in behaviour after a settings change is usually a power consequence rather than a fault. Cold weather reduces usable capacity sharply.
- Symptom boundary
- This record covers Dell XPS 16 9640 when it keyboard or trackpad is not working correctly. A different symptom on the same hardware, or this symptom on a different Dell product line, has its own record with its own causes and its own cited source.
Stop boundary
When this stops being a self-service repair
Continuing past any one of these costs more than the repair saves — in safety, in warranty, or in evidence a technician needs.
- !For any liquid spill: shut down immediately, disconnect power, do not attempt to switch it on to test, and seek professional attention. Powering on a wet machine is what turns a recoverable spill into a destroyed logic board.
- !Do not use rice, heat or a hairdryer on a liquid-damaged machine.
Evidence ledger
Sources behind this answer
Visible sources support the visible claims. Home Product Support records the publisher, the fact used and the review date; community reports can suggest an issue but do not become a published fact on their own.
Where the manufacturer's article stops. Dell Support publishes this as "Product support". Official Dell service-tag lookup, drivers, diagnostics and manuals. What that article does not carry is the model boundary — it is written for a product line, and XPS 16 9640 is the scope applied here. Where a control label, terminal, indicator pattern or reset sequence differs on your unit, the manual for that exact model is the authority, not this page and not the article.
Exact questions
Common follow-ups
My Dell XPS 16 fans are loud and it gets hot under load.+
The XPS 16 packs a powerful discrete GPU and CPU into a thin chassis, so under heavy load (rendering, gaming) it runs the fans hard and warms up to sustain performance — expected, not a fault. Keep it on a hard surface with clear vents, use a Dell 'performance' thermal profile in Dell's power software, and plug in the charger for full speed. If it is hot/loud at idle, check Task Manager for a runaway process.
My keyboard types the wrong symbols.+
That is a layout problem rather than a hardware one — if the keys register at all, the keyboard is working. The layout is set to a different region, which is why quotes, @ and # in particular come out wrong. Change the keyboard layout in the system settings to match your physical keyboard.
My trackpad stopped working.+
Check whether an external mouse is connected — many laptops disable the trackpad automatically when one is, and there is usually a keyboard shortcut toggling it that is easy to press by accident. If neither the trackpad nor the keyboard responds and nothing on screen is updating either, the system has frozen rather than the input failing.
I spilled liquid on my laptop and it still works.+
Shut it down now and disconnect the power. Liquid damage is progressive — corrosion continues after the spill, and the most damaging thing you can do is keep it powered while testing whether it still works. It needs professional attention, and rice, heat and hairdryers do not help.
Does this answer apply to every Dell model?+
No. It is scoped to XPS 16 9640. Dell PC family; use the service tag for exact BIOS, drivers, ports and warranty configuration.
What should I record before troubleshooting keyboard or trackpad?+
Record the complete model identifier, exact message or indicator, software/firmware where visible, the operating stage and what still works.
Why is a factory reset not the first step?+
A reset can erase accounts, networks, maps, schedules or preferences without distinguishing keyboard, trackpad. The ordered checks preserve that evidence.
When should I stop and use qualified service?+
Power off for liquid, swelling, heat or stuck power keys.
Answer for the exact device and software version shown above.