Damn, for a moment there I had hope it was something so simple. Tried that and it just flashes PC->->MD no matter what I do.
Edit: I did also try with the original Sony gumstick I still have that said low battery and it still didn't make a difference, but is it worth me draining one of the replacement gumsticks i have a bit and then trying it? I swear if its something that simple that I've missed, i'm gonna feel like such an idiot, haha
Edit 2: So, I ran a battery down just enough, and it actually seems to have worked. Wow, I somehow completely missed that in the manual but even then, when I originally got it a few days back when I plugged it in, it just charged without me pressing anything. Strange. But thank you @BearBoy !