start up light is on but no sound and no display

300zx1992 wrote:

macbook pro 15" no display, no sound, cannot reset nvram, with good battery.

? You do not say what exact Mac is this:

• Intel
• M1
• M2

there is no NVRAM on the M1/M2— equivalent Shut down, close the lid 30 secs+ , reboot as normal.

If no resolve try SafeBoot Use safe mode on your Mac - Apple Support to sort anomalies.

resetting the SMC Reset the SMC of your Mac - Apple Support see the details.

resetting NVRAM/PRAM Reset NVRAM on your Mac - Apple Support

If your Mac doesn't start up all the way

If your Mac doesn't start up all the way - Apple Support