Galaxy S24 Problems: Exynos Heat, Battery Drain and Fixes

Two people buy a Galaxy S24 on the same day, one in New York and one in London. Ten minutes into the same game, the London phone is noticeably hotter. That gap explains a lot of the Galaxy S24 problems people search for, because the two phones don’t have the same chip. The rest is mostly battery life that dips after each One UI update, plus the odd lock screen or lag bug.

The S24 and S24+ are also among the cheapest routes to a Samsung flagship in late 2026, with Samsung now selling Certified Re-Newed units on Amazon. If you’re shopping rather than fixing, skip to the last section.

Exynos 2400 or Snapdragon 8 Gen 3: find out which you have

S24 and S24+ models sold in the US, Canada and China run the Qualcomm Snapdragon 8 Gen 3 for Galaxy. Most other markets, including the UK, Europe, Africa and much of the Middle East, get Samsung’s own Exynos 2400. The S24 Ultra is Snapdragon everywhere. Heat and battery complaints come up more often on Exynos units.

To check yours, look at the model number in Settings › About phone or install a hardware info app that names the chip. The model number’s suffix also tells you the region, which our Samsung model number and CSC guide decodes. A Samsung Info report by IMEI gives the exact model, region and warranty date in one go.

Hot back, dimming screen, “Phone is hot”

You’ll feel it near the camera during games, video calls, long camera sessions or navigation. After 10 to 15 minutes of gaming, brightness drops or the frame rate falls. Sometimes a “Phone is hot” warning appears, or charging slows.

The S24 and S24+ are thin, with little room for cooling, and the Exynos 2400 has a reputation for running warmer than the Snapdragon version under sustained load. A day or two of extra heat straight after a big update is also normal while the phone re-optimises apps.

1. Update your apps in the Galaxy Store and Play Store, and install the latest system update from Settings › Software update › Download and install.
2. Set Performance profile para Light. Search “Performance profile” in Settings, because its location moves between One UI versions. You give up a little speed and get a cooler phone and better battery.
3. Lower graphics quality and frame rate in games. Don’t play on the charger.
4. Take thick cases off while charging, and use a Samsung-rated or good-quality 25W or 45W USB-C PD charger.
5. In Settings › Battery, find the apps using the most and move them to Background usage limits › Deep sleeping apps.
6. Hot while idle and unplugged? Test in Safe Mode (further down). If it’s still hot there, suspect the battery or another hardware fault.

Battery life drops after every One UI update

This has happened with almost every major release. In December 2024 Sammy Fans reported that S24 testers on the One UI 7 beta saw idle drain double, from roughly 0.4 to 0.5% an hour up to about 1% an hour. In April 2025, Asia Economy reported that Samsung paused the official One UI 7 rollout for the S24, Z Fold6 and Z Flip6 about a week after it began on 7 April, after users reported phones that wouldn’t unlock and abnormal battery drain.

One UI 9 on the S24

One UI 9, built on Android 17, started reaching the S24 series in Korea on 7 October 2026, with other regions following. Cybernews reports some S24 and S25 owners getting shorter battery life on it, especially faster idle drain. One Reddit user said screen-on time roughly halved. Sammy Fans suggests a battery can take about two weeks to settle after an update, and Samsung’s advice for problems that don’t go away is to book a service appointment. Our One UI 9 rollout tracker shows where your region is.

Work through these after updating:

1. Use and charge the phone normally for several days before you judge it.
2. Restart, and update every app.
3. In Settings › Battery, see what uses the most and deep-sleep the heavy ones under Background usage limits.
4. Reset what Adaptive battery has learned: turn Adaptive battery off, restart, turn it back on (search for it in Settings).
5. Switch off what you don’t use: Always On Display, Nearby device scanning, and high refresh rate (Settings › Display › Motion smoothness › Standard).
6. Wipe the cache partition from recovery (steps below).
7. Two weeks on and still bad? Run Samsung Members › Support › Phone diagnostics, read the battery result, and book a service.

Fingerprint, face or PIN ignored on the lock screen

When the lock screen stops accepting you right after an update, it’s nearly always software.

1. Force restart by holding Side + Volume down for about 10 seconds.
2. Install any newer update. Samsung fixed the April 2025 bug before it restarted that rollout.
3. Delete your fingerprints and add them again in Settings › Security and privacy › Biometrics.
4. A thick screen protector can block the ultrasonic fingerprint sensor. Try without it.

Completely locked out? The legitimate ways back in are your PIN, remote unlock through your own Samsung account, or a factory reset followed by signing in with your own Google account.

Lag and stutter: Safe Mode first, then a cache wipe

Safe Mode loads only Samsung’s own apps, so it tells you quickly whether something you installed is to blame. Open the power menu (hold Side + Volume down, or tap the power icon in Quick settings), long-press Power off, then tap Safe mode. If the lag, heat or drain goes away, remove recently added apps one at a time. A normal restart takes you out of Safe Mode.

Still slow? Clear the cache partition. It doesn’t touch your files.

1. Power off. On the S24 you have to connect it to a computer or charger with a USB-C cable.
2. Hold Side + Volume up until recovery appears.
3. Move to Wipe cache partition with the volume keys, confirm with Side, then pick Reboot system now.

Keep 15 to 20% of storage free. If it still feels sluggish, set the animation scales to 0.5x in Developer options.

Signs it’s the hardware, and where to take it

• Hot in Safe Mode while idle and unplugged.
• Battery shows “Bad” in Samsung Members diagnostics, or the back is lifting.
• Shutting down with more than 20% left.
• Lines or a green tint on the screen that survive a restart.

The S24 came out in early 2024, so most original warranties are over. Certified Re-Newed units carry a fresh one-year warranty, and Samsung Care+ adds accident cover. Otherwise go to Samsung service or an authorised centre that uses genuine parts.

Buying a refurbished or used S24

Samsung announced on 21 October 2026 that its Certified Re-Newed Galaxy phones are on Amazon.com from $489. The range covers the S24 (128GB and 256GB), S24+ (256GB and 512GB), S24 FE and S24 Ultra. Each unit passes 147 checkpoints, gets genuine Samsung parts including a new battery, and comes with a one-year manufacturer warranty. Samsung also promised the S24 seven years of OS and security updates, so software support has years left.

How that grade compares with ordinary used and “renewed” stock is in refurbished vs used vs renewed, and our used Galaxy model guide shows where the S24 sits against other models. Buying from anyone other than Samsung, go through this list:

• Run a Verificação de blacklist GSMA so you don’t buy a phone reported lost or stolen.
• For a US Snapdragon model, run a carrier and SIM-lock check.
• Make sure the IMEI on the box, in Settings and from *#06# all match.
• Run the battery and screen tests in Samsung Members while the seller waits.
• Watch the seller remove their Samsung and Google accounts.