Thank you gentlemen. The main power battery is brand new and has been working perfectly so I'm sure that's not the problem. I'm dumb so you'll have to explain a few things to me...

1. How do you reset the NVRAM?

2. Where is the reset button on these things? Does it have one? On the back panel it says "Reset=Shift, Fn, Ctrl & Start". Will pressing that reset the PMU/CUDA (whatever that is)?

3. How do you reset the PRAM again? Ctrl-option-PR is it?

4. Oh and what's this internal battery - is that the same as the PRAM battery?

Thanks [8D]