Battery dead after replacing PCM?

My boyfriend disconnected the negative connector on my battery, and I replaced the PCM and immobilizer. I hooked my battery back up. My lights go on, but when I try to start the car, my dash lights flicker, and it clicks.

Is this a bad PCM installation? Or did the battery die? Will it recharge now that it's hooked up? Or do I need to jump it? I just don't know.

It's a Honda 2001 Civic EX Sedan, if that matters.

Make sure the battery connections are clean and tight, then charge or try to jump start.