Bad MagSafe 2 or bad power board?

I bought a mid-2012 MacBook Air 11" that needed a new battery. Once I replaced the battery I noticed that the MagSafe 2 adapter was acting strange when connected. When I first connected it to the MacBook it did not light up. But after a minute it turned Amber. As it was charging the battery I noticed the light would go off and then back on. It seemed to be charging the battery whenever the light was off though. Even at full charge, when the adapter is connected it takes a minute before the light turns green.

I have tried the following:

Reset the SMC (a few times)

Reset the PRAM (a few times)

Ran AHT (it's clean)

Unfortunately, I don't have another adapter to test.

Before I make an appointment at the Genius Bar, I thought I'd ask if this sounds like an adapter problem or a power board problem.

Thanks in advance.