If you are technically oriented, this is a good guide to replace a 2015 MacBook battery. I did this work myself after reading the how-to. Delegating to an Apple repair person seemed fraught with too many places to mess up. Apple doesn’t have a good track record of owning up to mistakes.
Make sure to read the comments. There are a couple of issues in the how-to description that can lead to a bad outcome. Overall, it’s a good how-to guide.
For me, steps 15 and 22 were critical. Read the comments. If after replacement power doesn’t come on, it could be step 15 during re-assembly. Not easy to diagnose because damaging the logic board (despite following instructions and precautions) is always a possibility. If power comes on but the screen remains black, check step 22.
Most of the steps involve seating connectors into sockets for which there is no simple correctness check. Following the instructions carefully will help prevent damaging the laptop. And you can retrace the steps to debug problems.
The supplied tweezer is no good. You need one with grooves as shown in the picture. When re-inserting the antenna connectors, make sure that they are seated properly before pushing down. If you have magnifying equipment, use that to get visual confirmation. I used tactile feedback from my fingers to discern proper alignment. Try not to force it.
And be careful when re-inserting the connector. One end of the two indentations got a little bent (I did not notice) which resulted in a black screen when powering up. I used a heat gun (low setting) to separate the cable from the labtop housing. When re-assembling, first insert the connector (after closing the metal flap as instructed), verify that it’s properly seated, then re-attach the rest of the cable to the laptop housing. In the first try, I first re-attached the cable to the housing, then tried to insert the cable connected into the metal socket. Because of a lack of slack, the cable connector at one end got bent slightly. After identifying the problem, I had to straighten it/unbend out using my fingers. Hence it is easier to insert the connector first, then attach the rest of the cable to the laptop housing.
Emphasis on aligning the bracket correctly. What the pictures do not show is that underneath the flat part of the metal bracket (the area between the two screw holes) is a connector that needs to be accurately aligned. Aligning the two screw holes does not imply that the connector is seated correctly.
After I re-assembled my 2015 MacBook power would not come on. I thought I had damaged the logic board despite being careful and following instructions. Diagnosing the problem took a while. Retracing the steps and focusing on power supply I was able to determine that the metal flap which hides the connector underneath had not made proper contact.
What I did was to use a finger to get a tactile feel for the connector underneath the metal bracket aligning properly and then press down vertically when it seemed to be aligned. It’s a subtle tactile feel. After re-doing this step, I got power back. Be careful not to damage the connector as noted in the instructions.
I found “Recognizing & Disconnecting Cable Connectors”
useful, esp. for someone who has not used ZIF connectors and retaining flaps before. There are several retaining flaps that need to be opened. The first time is tricky as you need a sense of how much force to apply. I used the flat end of the provided spudger. Apply progressively firmer upward pressure until the retaining flap pops open. The first time is tricky, but straightforward thereafter.
I should have read the comments before using the provided 1.1 mm Tri-point Y00 bit. I almost stripped the screw but was able to use a small flat head bit to open the screw.
Ifixit: you may want to update this part in the instructions. Not everyone reads the comment section, esp. when it comes to specification of bits which is basic and must be accurate. This is one of the more critical ones in the procedure that can easily go south. The rest of the instructions are excellent.