How to fix a MacBook Pro 2015 that won't turn on after battery replacement?

Have you tried using the other USB-C ports, especially on the other side of the laptop?

Is the battery flex cable fully seated with the flip up latch flipped down to lock the cable in place? This flip latch is very easily damaged and many times will just get crooked & fall off. Some of battery flex cables also have another connector on the other end of the cable connecting it to the battery board as well....again with the same fragile easily damaged latching mechanism. Also inspect the cable for end tears or hard bends/creases. Without this connection, the battery won't work properly.

If the laptop is on like that and you perform the SMC Reset correctly, then the laptop will instantly power off. It may power on automatically after 10/15 seconds, or it may remain powered off. On a few laptops I couldn't get the laptop to power on again until I disconnected & reconnect the battery. These USB-C Macs are very odd beasts with lots of quirks and very difficult to troubleshoot.

Another option is to disconnect the battery (both the battery flex cable and the BMU screw). Power on the laptop using the power adapter. The system is likely to boot extremely slow and the fans will probably run at high speed. While the laptop is powered on, reinstall the BMU screw and carefully reconnect the battery flex cable. Let the system stay this way a while to see if the battery will charge. Just make sure you don't let the exposed internals make contact with any metallic or conductive surfaces or items.

When you started using the new battery, did you perform the calibration by letting it charge to 100% and leaving it at 100% for several hours? Then let the battery drain until the laptop powered off with the battery at 0% charge? Then reconnect the power adapter to allow the battery to charge to 100% and once more leaving the power adapter connected for several more hours before using the laptop normally? If not, then you may have inadvertently damaged the battery. This calibration or exercise is critical for third party batteries.

Of course, you may have just received a defective battery from iFixIt. Unfortunately the quality of third party Lithium Batteries is extremely poor....even batteries from respected vendors such as iFixIt and OWC will tend to have more issues & failures than an Apple OEM battery. Unfortunately Apple no longer supports the 2016 model, so your options were limited.

What makes this even more complicated is that even with a known good brand new Apple OEM official battery repair, I have seen these USB-C Apple laptops show the battery symbol even when the battery has sufficient charge. This tells me these Logic Boards have some sort of hardware/firmware issue where the Logic Board thinks the battery has disconnected itself since that symbol can appear when first powering on these laptops after the battery had been disconnected.

To1ken wrote:

if it’s not much to ask for, could you by chance put it in a step by step process, thanks ( would truly appreciate)

1. Remove all power from the laptop by disconnecting the power adapter
2. Disconnect the battery flex cable from the MLB (aka Main Logic Board).
3. Remove the T5 Battery BMU screw
4. Press & hold the laptop's power button for a second or two to drain any residual power
5. Connect the power adapter
6. Power on the laptop
7. Wait about a minute
8. Reinstall the BMU screw
9. Reconnect the battery flex cable to the MLB
10. Let the laptop stay powered on for at least 30 minutes in an attempt to charge the battery. If the laptop actually boots & you can log in, then wait until the battery charge level reaches at least 20%. FYI, the battery charge level shown on the login screen may not be accurate.
11. Don't let anything metallic or conductive make contact with the exposed electronics

If the battery is not charging, then try this modified procedure:

1. Remove all power from the laptop by disconnecting the power adapter
2. Disconnect the battery flex cable from the MLB (aka Main Logic Board).
3. Remove the T5 Battery BMU screw
4. Press & hold the laptop's power button for a second or two to drain any residual power
5. Reconnect the battery flex cable to the MLB
6. Connect the power adapter
7. Power on the laptop
8. Wait about a minute
9. Reinstall the BMU screw...be very careful not to dislodge or damage the battery flex cable
10. Let the laptop stay powered on for at least 30 minutes in an attempt to charge the battery. If the laptop actually boots & you can log in, then wait until the battery charge level reaches at least 20%. FYI, the battery charge level shown on the login screen may not be accurate.
11. Don't let anything metallic or conductive make contact with the exposed electronics

NOTE: When the battery is not connected in these USB-C Intel Mac laptops, the fans will run at high speed and system performance will likely be severely impaired.....so much so that the laptop may take hours to boot to the login screen or Desktop...it may not even make it that far & may appear to be stuck, but it is just running at a snail's pace.

You said 2015 model, right?

um, your picture does not show the MagSafe power adapter connected on the left side. Models that do not have USB-C ports (like 2015 modes) do not charge over USB. The MagSafe is required.

The battery BMU screw must also be disconnected prior to connecting the power adapter.

There is a possibility that you may need to reconnect the battery flex cable first & power on the laptop with the power adapter. Then very carefully reinstall the BMU screw....the flex cable will need to be gently moved a bit to allow the screw to be installed.

I only ever tried this procedure to jumpstart the charging on these Intel USB-C Apple laptops one time and it was some time ago. I know on the older Magsafe 1/2 laptops this trick worked wonders. I just never encountered situations where I had to do this with the USB-C Macs. I do know these USB-C Apple laptops act much differently when the battery is disconnected than older models.

I would try the easy safer way first by disconnecting both cable & screw to see what happens since trying to install the BMU screw risks the flex cable being damaged. It is very important that both are disconnected before trying either option so that the Logic Board loses all power.

The flex cable is just a signaling/data cable (communication with the battery as well as providing a temperature sensor), the real power comes from the connection of the metal tab from the Logic Board to the Battery Board where the BMU screw holds them together. However, without the signaling/data cable macOS and/or the firmware freaks out causing problems. Both connections are critical.

no, that likely means your directory has been corrupted by all the on off cycles. it can be fixed with Disk Utility.

The initial "chime" sound is generated in software when your Mac passes the Power-On Self Test. If the chime occurs and/or startup continues, your Mac is working. The screen should light up and draw a blank gray screen. Then on to the Disk Drive.

Accessing the Boot drive:

The solid Apple is not in the Mac's ROM at Cold start. The Apple logo can only appear when it is fetched in the first "blob" of software loaded from a 'magic' place on the boot drive, or re-run after a Restart. Then a whole lot of stuff is initialized, and the progress Bar moves part way across. After a cold start, seeing the solid Apple appear says your drive was able to produce the software that contains the Apple logo.

If a prohibitory sign appears at this point, it indicates some fundamental part of MacOS is damaged or wrong version.

Mounting the Boot drive:

The next step requires a lot of files by name, so the File System is initialized, and the Boot Drive is Mounted. If the drive directory is damaged, the drive can not be Mounted, so your Mac begins one pass of Disk Utility Repair. This will take an additional about five minutes. During this process, the progress bar may be extended, and will grow by an additional amount not seen on a routine startup.

at the end of that process (which should not take more than about five minutes), it will attempt to Mount the drive again:

-- if the drive Mounts, boot-up continues.

-- if the drive cannot be Mounted, your Mac can do nothing more, so it powers off.

-- if the process stalls, this may indicate you have Bad Blocks on your Rotating Magnetic Boot drive (if so equipped). The re-reading of Bad blocks can take a very long time (on the order of a quarter minute for each Bad Block).

To1ken wrote:

Hey thanks for the step by step process, I just ran into one small problem, my MacBook shuts off when hitting half way in the white bar while trying to boot. Is my MacBook finished?

If the battery is disconnected, or partially disconnected, or even has some power related issue if the battery is connected, then all bets are off on how these Apple USB-C laptops behave. These USB-C Macs are not anything like the older Macs. The old rules don't necessarily apply or work here. Troubleshooting hardware issues with the USB-C Macs is very difficult. Definitely not something that can be easily diagnosed first hand, much less online with absolutely no direct access or observations.