did you follow this guide? [guide|108512]
Did you note the warning?
[quote]***To avoid logic board damage***, when your Macook repair is complete ''but before powering it on'', connect it to low-voltage power using a 5-Watt iPhone charger and a USB-C to USB-A cable. ***These accessories are not included with your MacBook, so make sure you have them ready before you begin.***[/quote]
See if that fixes things.