Stylus Not Working? Batteries, Bluetooth Pairing, and Fn-Lock Keyboard Quirks

When a stylus stops working, check its power source before anything else. Most active pens run on a AAAA battery or a small internal rechargeable cell, and a dead battery is the single most common reason a pen loses pressure sensitivity or stops registering entirely. If the pen connects over Bluetooth and the tablet still responds to finger touch, verify the pairing next — a dropped Bluetooth link breaks the pen while leaving the touchscreen fine. A related but separate complaint, function keys doing the wrong job (F5 dimming the screen instead of refreshing), is almost always the Fn-lock toggle, not failing hardware.

Passive vs. active styluses: know which one you’re holding

Troubleshooting starts with identifying the pen type, because each fails differently.

A passive (capacitive) stylus is essentially a rubber-tipped finger substitute. It has no electronics, no battery, and no pairing. It works on any capacitive touchscreen by conducting the same tiny electrical charge your fingertip does. If a passive stylus “stops working,” the problem is the tip (worn or damaged conductive material), the screen, or a thick screen protector — there is nothing inside the pen to fix.

An active stylus contains a powered digitizer circuit in the tip. That circuit is what enables the features artists and note-takers care about: pressure sensitivity (line weight changes with how hard you press), tilt detection, hover cursors, and palm rejection. All of that electronics needs power, which is why active pens take a replaceable AAAA battery (common in Surface-style and many Wacom-style pens) or charge internally over USB-C or by docking magnetically to the tablet.

Many active pens add a Bluetooth radio on top of the digitizer. On most designs, Bluetooth carries the extras — barrel-button shortcuts, eraser-end clicks, quick-launch gestures — but some tablets rely on the paired connection for full pen input. Either way, when a pen that normally pairs suddenly stops drawing while finger touch works, the pairing is the first suspect.

Feature	Passive stylus	Active stylus (non-BT)	Active stylus with Bluetooth
Battery required	No	Yes (AAAA or rechargeable)	Yes
Pressure sensitivity	No	Yes	Yes
Pairing required	No	No	Yes, for full function
Works on any capacitive screen	Yes	No — needs compatible digitizer	No — needs compatible device
Common failure	Worn tip	Dead battery	Dead battery or dropped pairing

Battery first: the check that solves most tickets

Pressure sensitivity is the canary. When an active pen still makes marks but every stroke comes out the same width, or strokes start skipping, the pressure sensor is browning out — classic low-battery behavior. When the battery dies completely, the pen goes silent even though it looks physically perfect.

The technician’s first move on any active-stylus complaint:

1. Replace or charge the battery. Unscrew the barrel and swap the AAAA cell, or seat a rechargeable pen on its charger/magnetic dock for at least a few minutes.
2. Confirm orientation. AAAA cells are small enough that users regularly insert them backwards.
3. Check the tip (nib). Nibs are consumables. A worn, cracked, or partially unseated nib can stop pressure readings even with a fresh battery. Most pens ship with spare nibs and a removal tool.

Only after power is ruled out should you move to pairing, drivers, or the tablet itself. This ordering matters on the exam: the first check for a battery-powered stylus that lost pressure sensitivity is the battery.

Bluetooth pairing: when the pen dies but touch still works

The key diagnostic split: does the touchscreen still respond to fingers? If yes, the screen and digitizer layer are healthy, and the problem is isolated to the pen or its connection. For a Bluetooth-paired pen, verify pairing first:

• Open the tablet’s Bluetooth settings and confirm the stylus still shows as Connected, not merely “Paired previously.”
• Toggle Bluetooth off and on, or forget the pen and re-pair it. Pairings drop after OS updates, after the pen’s battery fully discharges, or when the pen has been paired to a second device (most styluses hold only one pairing at a time).
• Rule out interference and distance — Bluetooth is a short-range Wireless Personal Area Network (WPAN) link, the bottom rung of the WPAN/WLAN/WWAN range ladder, and a pen that was paired in another room may have timed out.

If re-pairing fails, fall back down the stack: charge the pen, restart the tablet, and check for pen-driver or firmware updates in the vendor’s pen app (Surface app, Samsung Notes/S Pen settings, Wacom Center, and similar utilities all expose pen battery level and firmware).

Also check the software side: some drawing apps have their own stylus toggle or a “draw with touch” setting that, when misconfigured, ignores pen input while accepting fingers.

Fn-lock: when F-keys stop acting like F-keys

Laptop and tablet-keyboard top rows are dual-purpose: each key is both a function key (F1–F12) and an action key (brightness, volume, airplane mode, media control). Which personality is primary is controlled by Fn-lock — a toggle usually mapped to Fn+Esc (look for a small padlock icon on the Esc key) and configurable permanently in UEFI/BIOS firmware settings, where vendors label it “Action Keys Mode,” “Hotkey Mode,” or “Function Key Behavior.”

So when a user reports that F5 now changes brightness instead of refreshing, and every other F-key has similarly swapped jobs, nothing is broken. The Fn-lock state flipped — usually from an accidental Fn+Esc press. The best first step is to toggle Fn-lock back, not to reinstall drivers or replace the keyboard. If the user wants the change to survive reboots, set the preferred default in firmware setup rather than relying on the keyboard toggle.

This lands in the same troubleshooting family as stylus issues because both are mobile-device input problems where the fix is a mode or connection state, not hardware replacement.

How the 220-1201 exam tests this

• “Active stylus lost pressure sensitivity — what do you check FIRST?” The answer is the pen’s battery. Distractors will offer re-pairing, driver reinstalls, and screen replacement; the exam wants the least-invasive, most-probable cause first — the discipline behind the CompTIA troubleshooting steps.
• “Bluetooth stylus stopped drawing but finger touch works — FIRST check?” Working touch proves the screen is fine, so verify the Bluetooth pairing/connection status. A dead digitizer or cracked screen would take touch down too.
• “F5 adjusts brightness instead of refreshing, and other F-keys match — BEST first step?” Toggle Fn-lock (Fn+Esc or the firmware setting). Recognize this as a mode toggle, not a failed keyboard.
• Passive vs. active discrimination: expect a stem describing a stylus with no battery compartment working on any phone — that’s passive, and it can never provide pressure sensitivity.

Stylus and input troubleshooting is Hardware and Network Troubleshooting territory — the full 220-1201 study guide shows how the domains and question types fit together. Quick-win items like these are free points if you’ve seen them in practice first.

Quick reference

• Active styluses need power: AAAA battery or internal rechargeable cell. Battery is the FIRST check for lost pressure sensitivity.
• Passive capacitive styluses have no battery, no pairing, and no pressure support — worn tips are their only real failure.
• Bluetooth pen stops drawing but touch works → verify pairing/connection status before anything else.
• Most styluses hold one Bluetooth pairing at a time; pairing to a second device silently drops the first.
• Worn or unseated nibs mimic battery failure; nibs are replaceable consumables.
• Fn-lock (often Fn+Esc, padlock icon) swaps F-key and action-key behavior; a firmware setting makes the choice permanent.
• Vendor pen utilities show stylus battery level and deliver pen firmware updates.