Galaxy S24 Ultra Problems: Green Line, Drain, Slow Charging Fixes

A thin green line runs top to bottom across the screen. You restart, and it’s still there on the Samsung logo. That is the Galaxy S24 Ultra problem people dread most, but it isn’t the one they report most often. Since the One UI 8.5 and One UI 9 updates, battery drain and slow charging have taken over the forums, with overheating close behind.

The S24 Ultra launched in January 2024 with a 6.8-inch QHD+ AMOLED display, the Snapdragon 8 Gen 3 for Galaxy, a 5,000 mAh battery, 45 W wired charging and a titanium frame. Samsung promised seven years of OS and security updates, so it’s now getting One UI 9 based on Android 17. Plenty of them are on the used market, too. Some of the problems below respond to settings. One doesn’t.

The green line: why no setting will fix it

A vertical green line (sometimes pink or white) that stays put when you scroll and appears on every screen, boot logo included.

Samsung flagships have had green-line reports for years. Sammy Fans reported a brand-new S24 Ultra with a vertical green line in February 2024, a few days after activation. In April 2024 TechRadar covered owners of several Galaxy models who blamed the line on a software update, and Samsung’s advice then was to visit an authorised service centre. Whatever sets it off, a line that survives a restart and shows on the boot screen is a panel or display-connector fault.

1. Restart and watch the Samsung boot logo. If the line is there too, it’s hardware.
2. Install pending updates in Settings › Software update › Download and install. It won’t remove the line, but the service centre will ask you to do it.
3. Back up with Samsung Smart Switch or Google. A screen replacement can involve a reset.
4. Check the warranty before booking. A Samsung Info report shows warranty dates and country of sale from the IMEI, and our guide to checking Samsung warranty by IMEI explains each field.
5. Book with Samsung or an authorised partner, and ask for a genuine Samsung display assembly.

Two updates, two waves of battery complaints

After the July 2026 One UI 8.5 update, Tech Advisor highlighted a Samsung Community post describing “massive battery drain” on an S24 Ultra. Samsung hadn’t officially acknowledged it at the time. Then One UI 9 arrived, and Cybernews reported S24 and S25 owners describing worse battery life and faster idle drain. When one S24 Ultra owner complained on X, Samsung told them to book a service appointment.

Some drain right after a big update is expected. The phone re-optimises apps and rebuilds caches, and Sammy Fans suggests that can take around two weeks. So charge it overnight for a week or two before deciding something is broken. If it’s still bad after that:

1. Install the latest patch in Settings › Software update. Samsung often fixes drain quietly in a follow-up build.
2. Open Settings › Battery to see usage since the last full charge. Tap any app with odd numbers and set Background usage to Restricted or Optimised.
3. Turn on Settings › Battery › Background usage limits › Put unused apps to sleep.
4. Run Settings › Device care › Optimise now to close stuck background processes.
5. Wipe the system cache partition. Power off, connect the phone to a computer with a USB-C cable, then hold Volume Up and the Side key until recovery mode appears. Choose Wipe cache partition (not factory reset) and reboot. Owners in the Tech Advisor report shared this as one of their workarounds.
6. Boot into Safe Mode: hold the Side key and Volume Down, long-press Power off, tap Safe mode. If the drain stops there, a third-party app is behind it.

From 70 minutes to three hours: slow charging

In the same Tech Advisor report, one owner said a full charge that took about 70 minutes in testing now took up to three hours, and blamed One UI 8.5. Others notice the screen no longer says “Super fast charging”, or that charging stops around 80%.

Sometimes the update is to blame. More often it’s something ordinary. The S24 Ultra only reaches 45 W with a USB Power Delivery charger that supports PPS and a 5 A USB-C cable. A non-PPS charger, a worn cable, lint in the port, a battery-protection setting or an ageing battery will all slow it down.

• In Settings › Battery › Charging settings, make sure Fast charging (and Super fast charging) is on.
• Look at Settings › Battery › Battery protection. Maximum stops at 80% on purpose. Adaptive and Basic behave differently.
• Use a 45 W PD PPS charger with a 5 A cable. A 25 W or generic charger still works, just more slowly.
• Power off and clear lint from the port with a wooden toothpick or soft brush. Never metal.
• Charge with the screen off. Samsung slows charging when the battery is warm, so gaming on the cable defeats the point.
• Try a charge in Safe Mode to rule out an app keeping the processor busy.
• Check battery health in the Samsung Members app › Support › Phone diagnostics › Battery status. “Bad” means it needs replacing.

Running hot during games, video or charging

The frame gets hot, the screen dims, the camera warns it’s about to close, or charging pauses. The Snapdragon 8 Gen 3 is powerful, and long gaming sessions, 8K video, navigation in direct sun or using the phone while it charges all push it hard. For a few days after an update, background optimisation adds to the load.

Take thick cases off while charging or gaming, and close camera, navigation and game apps you aren’t using. In Settings › Device care › Performance profile, pick Light if your build offers it. Lowering the resolution and turning off Always On Display help here too. Keep apps updated from the Galaxy Store and Play Store, because a buggy app version is a common cause.

A phone that gets hot while idle and off the charger, or reboots from heat, is different. That points to the battery or board, and it’s a service-centre job.

Which problems need a repair?

Book a repair when the green line shows at boot, when charging stays slow with a known-good 45 W charger and cable after you’ve cleaned the port, when battery status reads “Bad”, or when the phone overheats at idle. Most original S24 Ultras are past the standard warranty now, but some have Samsung Care+ or an extended retailer plan, so check the IMEI first. A Samsung Info S2 report confirms the original model code and country, which affects parts and service eligibility.

Buying a used or Certified Re-Newed S24 Ultra

In October 2026 Samsung brought Certified Re-Newed Galaxy phones to Amazon.com, including the S24 Ultra in 256 GB and 512 GB. According to Technobezz, prices in the programme start at $489, and every phone gets a new battery, a one-year limited warranty and 147 quality checks. That’s lower risk than a private sale. Check any S24 Ultra before paying anyway:

1. Start with a free All-in-one Basic Info check so you know the model matches the listing.
2. Dial *#06# and run a GSMA blacklist check on the IMEI.
3. If it came from a US carrier, run a carrier and SIM-lock check.
4. Open a plain white image and look for lines, burn-in and tint. Then test the fingerprint sensor, which often fails on non-genuine panels.
5. Go through the rest of the used Samsung buying checklist in person.