I've had my 704 for about two and a half years now, and never had any trouble with it. I use it daily to watch videos in the train to and from work.
Two days ago, while transferring new video files (through the DVR station/USB), there was an audible 'clack' from the archos. The file transfer stopped immediately, my computer claimed the device had been disconnected. The archos immediately shut down (no 'shutting down' message or delay, just instant black screen).
It then did not react to my pushing the power button, so I removed it from the DVR station and tried again, with no result. I then removed and replaced the battery, and was rewarded with the 'ARCHOS' logo, followed by a short blink of white screen (a second or so) and then again shutdown. So I again removed the battery and pressed the reset button. No change.
My first idea was a fried battery, so I got my replacement battery and swapped them (I have two batteries that I swap once a week, until now, they both held about four hours video playing charge). After again hitting the reset button for 5 seconds or so, the device actually powered up into the 'calibrate touchscreen' thing, and then to the normal interface. I assumed everything was fine.
So I charged the device (with battery of course) over night in the DVR station and took it to work next day. In the train, it shut down (regularly, with 'shutting down' message) after about two minutes of video playing. Upon restarting, I noticed that it was showing a totally empty battery. I assumed that maybe I hadn't plugged it in right, or that maybe the DVR station was fried.
So the following evening (yesterday), I disconnected the DVR station and charged the 704 directly. While it's plugged in, it runs perfectly, the CHG light is on to show it's charging, and the battery indicator on screen also shows the little spark icon meaning 'charging'. However, even after several hours, if I disconnect the device it shows an empty battery and shuts down after a few seconds.
I since performed a complete format and factory reset, without any effect.
So, what could the problem be?
I doubt that it's just dead batteries, as it happened instantly and simultaneously on two batteries.
I doubt it's anything to do with the DVR station, as the symptoms are the same when charging directly.
My best guess is that somehow the device isn't actually conducting power to the battery when it's charging, thus the batteries are in fact empty. Maybe the 'clack' I heard was a blown component that's responsible for connecting the device to the battery (strange that it still work for a few minutes though).
Alternatively, it may be a faulty sensor reporting an empty battery even when it's fully charged, resulting in a controlled shutdown from the device.
Any ideas? And should I send it in for repair, or is that probably going to be more expensive than buying a new device?