You can't remove the battery on the 2015 without disassembly, you don't need to do that.
https://support.apple.com/en-ca/HT204063
NVRAM
Shut down your Mac, then turn it on and immediately press and hold these four keys together: Option, Command, P, and R. You can release the keys after about 20 seconds, during which your Mac might appear to restart.
- On Mac computers that play a startup sound, you can release the keys after the second startup sound.
SMC
If the battery is nonremovable:
- Choose Apple menu > Shut Down.
- After your Mac shuts down, press Shift-Control-Option on the left side of the built-in keyboard, then press the power button at the same time. Hold these keys and the power button for 10 seconds. If you have a MacBook Pro with Touch ID, the Touch ID button is also the power button.
- Release all keys.
- Press the power button again to turn on your Mac
Hardware Test
https://support.apple.com/en-ca/HT201257