I'm hoping somebody has encountered this, before - it really relates to changing the battery, but I'll give a bit of history / context.
I've had an AV440 for a good few years, and it's served me well. A while back, I decided to upgrade the hard drive (I'd always intended to, once the warranty had expired, but it took me some time to bite the bullet and do it). I put in a 120G hard drive, which was fine - everything worked OK.
Around that time, though, and battery life seemed to sharply drop off, so I decided to change / upgrade the battery.
The first one I bought was a Cameron Sino replacement upgrade (think I bought it from ebay) and I carefully cut the wires to the original battery - leaving a generous amount of length from the AV440's circuit board, soldered and heat-shrunk the new battery, and it seemed to charge OK (charge light stayed on permanently for a while, then at some point, changed to flashing, indicating the battery was fully charged).
But it wouldn't power up - the power light comes on when you press and hold the power button, but goes out as soon as you release it. After doing some reading / research, I'd read comments about some aftermarket batteries causing problems, I decided to try a different one, and got one from one of the recommended sites in the UK (advancedmp3players, I think). When that came, I connected up that battery, with exactly the same results - same charging behaviour, but the device won't power on.
Has anyone encountered this before?