Thinkpads Forum

Rebuilding a parts-unit X1 Carbon Gen 4. So far replaced screen (known bad), coin cell battery (old) and main battery (reported by system as dead), New battery is off eBay. Installed the battery and the system booted right up, 84% charge, good battery health, and all looked fine. Ran it down in level a bit to work on other things, and then tried to charge.

When I insert the charger and the laptop is running, the power button starts flashing 2-blinks, pause, 2 blinks and the "plugged in" icon starts flashing screen. System does NOT start to charge. If the system is off, the orange charge light near the power port comes on solid, but system still does not charge.

I have done the searches and find nothing quite like this.

I have tried the power drain 20-45 secs, no joy. Held reset button for 10 secs, no joy. Disconnected coin cell battery for 10-secs, no joy. Disconnected and reconnected battery, no joy. Don't see anything in BIOS, or Lenovo Vantage (battery set to start charging at 75% but it doesn't). Tried two different Lenovo chargers, 65W and 90W no change.

Bad battery? New one on order, but ....

Any help or thoughts on this issue? The UG doesn't address the 2-flashes on the power button, just says a power issue is at fault.

Updates

I cleaned all the battery connectors with DeOxit, ran all the updates, left it off but plugged in to charge for 8+ hours with no change. Charge is decreasing to the point of going on low power mode, but battery is not charging. And power button continues to flash 2x pause then 2x then pause....repeatedly when running and plugged in. Disconnect the battery and laptop powers on and runs fine (mostly, more on that later) but that's not a viable solution. New "genuine Lenovo" battery on order from eBay. We'll see.

The "runs fine" issue is also troubling. This laptop, i7-6600 8gb ram is a dog. Dunno why but it is incredibly slow. It will boot, give you the Windows tune, then the screen blanks for 10-15 seconds before you get the PIN prompt to start. Even once started, Windows is sloooooooooooow. Things like menus take often almost a minute to appear. Click on a taskbar program and it may or may not load, and if it does may take minutes to appear.

I need to get the new battery and charging issue fixed first. Also on order is a 500 GB M2 Sata drive to replace the OEM 128 GB drive, and then probably a full Windows reset.

Once it learns how to charge.

But regardless of the charging issue, this Gen 4 is a dog compared to my X1 Carbon Gen 3. Not sure why Lenovo considered this the next generation upgrade.

Do you have the 45W charger, or the 65W one?

Many older Thinkpad BIOSes lock down the processor to a low clock speed when running without a battery and have a low-wattage charger connected. For the X seris from the X61 to X230, the low-wattage charger is the 65w, so it needed a 90w charger to run at full speed without batteries. I don't know if it's the same case for the X1 Carbon Gen 4.

axur-delmeria wrote: ↑

Mon Jul 14, 2025 9:11 am

Do you have the 45W charger, or the 65W one?

I have used it with both during this rebuild and don't think there is any difference in performance. 90W right now. FYI, OEM was a 65W charger according to the PSREF, and it was slow as molasses then.

Any help with the blink-blink-pause, blink-blink-pause sequence?

Scorpion8 wrote: ↑

Mon Jul 14, 2025 6:43 pm

Any help with the blink-blink-pause, blink-blink-pause sequence?

Does that happen regardless of which charger you use?

axur-delmeria wrote: ↑

Mon Jul 14, 2025 8:13 pm

Scorpion8 wrote: ↑

Mon Jul 14, 2025 6:43 pm

Any help with the blink-blink-pause, blink-blink-pause sequence?

Does that happen regardless of which charger you use?

Yes. Only when powered on, the sequence starts. If the laptop is shutdown, I get the steady orange "changing" status light on the side. But it doesn't charge. As soon as I power it on, the blinking starts and does not matter which charger is in use.

Still awaiting a new battery. No other updates.

So other issues noted while waiting for the new battery (which is going on a world tour, thanks USPS!):

Boot -- Laptop boots fine on wall-power, but after Windows music chime, the screen stays blank for an inordinate amount of time (say 10-15 seconds) between when the Lenovo logo disappears and the Windows lock screen pops up.

Boot -- Sometimes when the system boots and gets to the lock screen PIN, the keyboard does not respond to input to enter the PIN. A reboot usually cures this, but you never know when it will happen and when it will work fine.

Speed -- This thing is slow. Clicking on a program sometimes involves a wait of 20-seconds or more before any activity is seen. I have run the task manager processes and there doesn't seem to be anything unusual happening. Sometimes nothing happens and you have to re-double-click on a program to launch. It is only 8GB but even my Thinkpad Yoga 11E is faster than this on a Celeron N500.

Any experience with these issues before I try a complete Windows reset?

That laptop just has a lousy CPU, i7-6600U (only 2 cores, soldered) looks good on paper.
Does it have 4, 8 or 16GB RAM?
My oldie M900 (mini-desktop) has a 'measly' i5-6600T (4 cores, socketed) with 16GB RAM and literally FLIES through everything.
Compare those and weep!
You are probably also trying to run W11?
If so, use W10 Enterprice LTSC 2019 or 2021 instead.
Or be bold and go to Linux Mint.

Or be VERY bold and put MacOS on it!
I recently Hackintoshed my T480 (i5-8350U, iGPU, 32GB RAM) with MacOS Ventura.
Used an external SSD and it took me less than 2 hours to have it fully up and running.
Upgrade to MacOS Sequoia is next.
All that just for fun (I'm retired with plenty time on my hands).

This one runs Win11 and has just 8GB RAM, and yea that is a small amount today, but the performance is beyond miserable when compared to much lesser pieces of kit. Like I stated, a Celeron N500 in a Yoga 11e running Win11 outperforms this one. My T420 will scream past this machine, as will a similar configured X1 Carbon 3rd Gen. And some of the issues, like the long screen delay upon startup, and the glacial speed of responding to mouse clicks at times is a sure cause for Tourettes Syndrome. And no one has provided any info on the two power button flash sequence, so am wondering if there is an internal issue before I just throw in a new battery.

You already provided the answer:

Disconnect the battery and laptop powers on and runs fine...

So we just wait until you have a new/better battery.

RealBlackStuff wrote: ↑

Thu Jul 24, 2025 11:49 am

You already provided the answer:

Disconnect the battery and laptop powers on and runs fine...

So we just wait until you have a new/better battery.

Well, by "runs fine" I mean it runs. Performance wasn't compared to on-battery versus no-battery-line-power.

Machine performance issue is 50-60% solved. This machine came from a business recycler, which got me thinking. Sure enough the drive encryption setting was ON, even after a Windows reset. This caused the lil' 2-core CPU to churn excessively. It is not a seamless background process, maybe on a late gen CPU but not on this i7-6500 2-core chip. Turning device encryption OFF resulted in a marked improvement. Oddly still not as fast as my Gen 3 X1 Carbon, which is odd, but there ya have it. Small improvements. This will never be my main device anyway.

An update. Compared my Gen3 X1 Carbon (8GB, i5-5600) to this Gen 4 X1 Carbon (8GB, i7-6500) and the Gen 3 blows this "newer, faster" machine away. Besides disk encryption, what could be throttling this machine so much? Is there a BIOS setting that I am missing?

BTW, "new" battery is here but not installed yet. Man, I wish I got those airline miles for my packages.....

RealBlackStuff wrote: ↑

Thu Jul 24, 2025 11:49 am

So we just wait until you have a new/better battery.

New battery (Lenovo "branded") installed. Still shows two-flashes-and-pause, two-flashes-and-pause on power button. Charging icon appears intermittently but it is NOT charging, down from 74% upon install to 71% while idling doing nothing.