Readynas duo v2 battery death symptoms?

Okay. Switched power supplies, and it works. Put back on the original power supply, and it doesn't, neither driver spins up. Just beeps every few seconds. wouldn't power down by front panel power button, either. Unplugged; removed right bay drive. Plugged back in, powered up, left bay drive spins up and works fine, shows up in Raidar showing not redundant. Repeated procedure with the other drive in only the right bay, also works. But with both drives in, neither will spin up, just beeps. So you're right, likely inadequate power for both drives with the power supply that came with it. It's an off brand one, so I will have to order a new one. It was just odd, that it would work fine throughout initially installing the drives, all of a sudden, the power supply just fails now. Perhaps that was why it was listed as 'not working'. I'll put it through some testing to see if it holds up; if so, I got a bargain for $40. If not, I still got two drive caddies out of the deal. Thanks for reminding me to go through all the steps; I, of course, just assumed what worked fine yesterday, would still work fine today. 

While I'm on the subject, considering the prospective age of these, should I consider replacing the fan and that battery before I put it into service? Just for routine maintenance, as those are the only parts that I know that might normally wear out. I have two v1's which are vintage around 2007, which I suppose also have batteries that old. But if the only thing they do, is hold the time when the units are unplugged, I suppose that there's no danger of their eventually dying causing any problems other than resetting the date should they expire. The fans, OTOH, well, I guess that would also be safe to leave them as is until failure, as the NAS will just shut down if it gets too hot, and I can replace them at that time if I still want to use those NAS.