"Why does my Mac only work when it's plugged in?: my macbook doesn’t turn on or stay on unless it’s connected to the charger but also it won’t charge, i changed out the battery but still have the same problem any help?"
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Troubleshooting Mac Power:
Some Links that may Help...
A. Black Mac Screen:
Go Here: If your Mac doesn't Turn On or Start Up - Apple Support
Using External Devices: Try Resetting the SMC and NVRAM, but this time, using an external keyboard. Connect an external monitor and see if you get an output.
B. Mac Power Issues:
Try a New Charger:
If it is currently charging from a charger, then use a new charger:
C. A Few Links to Refer to Power: