MacBook repeatedly starts when closed.

When closing the MB it goes to sleep but repeatedly wakes up, in 1 case completely draining the battery. This occurs when it is stand-alone, with no devices attached and whether on battery or mains.

This problem got worse after I replaced the top case. I replaced this because the enter function was occurring without being pressed. The enter key problem seems to have been solved.

I assume the current problem is something to do with the magnetic catch triggering sleep?

How do I check and fix it.

Thanks,

Stephen