Thanks for responding guys.
Gardenstate. Thanks for the advice on battery usage, unfortuanately I bought both 505's second hand, so the batteries where already lasting half as long. I never used the audioplayer (that's what my iPod is for

) and charged it every four days or so.
Jakeluck. As soon as I broke the first 505, I trawed through the forums and found yours and other's posts about this. Thanks for the advice, but the ribbon's torn about halfway through. It was fine when I removed the outer case, but it seems to be the process of putting it back in, that pulls it the wrong way and tears it

.
So now I have two broken 505's. Maybe I should sell 'em on eBay for those who need new screens.
...Oh and I contacted NewPower99 about this, they weren't too bad. They said that they'd never heard of anyone having any trouble like mine before, but they refunded me the cost of the battery, so that's something I suppose.
Maybe I'll trawl round the shops looking for the elusive PRS-650
Roguexuk