My macbook cut out. I tried the SMC reset and a different lead and nothing worked, I read on a forum if you disconnect and reconnect the battery it can fix a power issue.
I done it and I worked - heres how to do it.
If it doesn't work for you that's not my fault -
DONT REMOVE THE BATTERY YOULL LOOSE YOUR WARRANTY. If it's still under warranty get Apple to do the work.
I used to a stanley blade to do the screws because none has a screw driver that small for the screws at the back.
Make sure the longer screws go back in the same holes they came out of. Let me know if it worked for you!