late 2008 unibody macbook weird power issue

[dude4]

i have a late 2008 macbook (that had no battery but i bought one) that
it wont turn on by the power adapter and the adapters light is never on in any color. but while connected to power the battery indicator lights were flashing green indicating to me it was getting power

i went to the apple store and the genius says its the magsafe board because as it would power on with there test battery and not there test power adapter
both him and I have tried resetting the SMC, he also took it in back and made sure the magesafe board is connected correctly

here is where it get weird, I noticed once i got it home with a new battery that it would boot off battery, but then if i plugged in power adpater and pulled the battery it would run from power
it then says its running off battery but thwn system profiler says there is no battery(which is correct)
eitherway it still wont charge the battery

any ideas