MacBook not turning on after speaker replacemen ‘URGENT HELP’

Hello, hoping everyone is in great health.

I had a bad speaker in my Macbook 2015 15’inch Retina. So i planned to change it myself. I took out the back cover removed the fan but realized i forgot to take the battery cable out so the laptop turned on then i shut it off through the power button and took the battery cable out took the fan out replaced the speaker then i had somewhere to go so i left the mac open for an hour or two then came back put it all back together but not it does not turn on. No fan, no keyboard lights nothing. When i plug in charger does work it goes orange / green . But the laptop does not turn on

I reset the SMC thing. No hope

Pressed the power button for 10/30/60 seconds nothing

Removed & reconnected the battery terminal nothing

Can someone please guess what could go wrong?. I’m sure I didn’t damage any wires since this was not the first time i was repairing something.

I need to sell it to a customer tomorrow now i’m stuck with a broken mac