Try the SMC reset on the mac,
https://discussions.apple.com/docs/DOC3604#:~:text=Shut%20down%20the%20computer.,button%20at%20the%20same%20time.
If you are comfortable with taking the back off unplug the battery and plug it back in. and try start it again with the charger plugged in.
if this doesn't work you can try plug it into the charger and start it without the battery plugged in.