I have an Early 2015 MacBook Pro Retina, which I hard-restarted earlier (holding the power button) due to a software crash. It turned off just fine but refused to turn back on again (no backlight, no drive noise, nothing). I thought I remembered a fairly high battery percentage, but to be sure I connected it to power and tried again, unsuccessfully. I left it for a while, then tried an SMC reset with the adapter connected.
This seemed to work, since the power indicator light turned green for a few seconds (which makes sense). This somewhat fixed the issue in that the machine actually showed signs of life when I tried turning it back on, but it would just display a black screen with the red/white low battery symbol and the lightning bolt underneath it.
I left it charging for a while and then had to disconnect it for about an hour to take it with me. When I plugged it back in, it actually powered on and booted up successfully. However, the battery indicator is now perpetually at 0%, and the battery info is rather disturbing:
Model Information: Manufacturer: SMP Pack Lot Code: 0 PCB Lot Code: 0 Firmware Version: 702 Hardware Revision: 1 Cell Revision: 3217 Charge Information: Charge Remaining (mAh): 0 Fully Charged: No Charging: No Full Charge Capacity (mAh): 1708 Health Information: Cycle Count: 564 Condition: Replace Now Battery Installed: Yes Amperage (mA): 0 Voltage (mV): 8421
I've also tried an NVRAM reset, with no change. I read somewhere that doing an SMC reset while booted up and logged in solved similar problems in some cases, but that seems a bit risky as far as my data is concerned.
I'd really appreciate any ideas - thank you!
I should also mention that the charger light isn't doing anything unusual (i.e. not turning on when the charger is connected). Also, the machine is noticeably slower than when everything was working normally.