Replacement Battery for Zen Vision M

My husband and I both have Creative Zen Vision: M 30GB. We have tried the replacement batteries by HQRP and a Camerson Sino. Neither battery would charge by any method for my husband's Zen. When we opened mine for the first time last night, we found that the hard drives were different (amongst a few other things, rest were minor). We received ours within about 3 weeks of each other, from the same source. The only difference, I thought, was the colors. Mine is blue. When he put the Camerson Sino into my Zen, it worked. It was fully charged - most likely from being hooked up to my husband's Zen for about 20 hours on the USB-computer charger. The computer, nor the Zen would recognize the battery in either case. It would not function. I have not found any information regarding this situation. However, either will work when hooked up to AC power regardless of what battery is in it and how low the charge is. Through the awesome power of the Creative Labs X-fi 2.1 stereo system specifically designed for the Zen Vision M, I am able to connect (through the mini USB cable connector in the back of stereo base) the Zen to a computer. The Zen is now able to function, upload and access.
When replacing a battery and running into trouble, there are suggestions to downgrade the firmware to the 1.41.02 (I believe, see amazon.com reviews), one should not use Windows Vista to upgrade to the latest firmware (as of now, it is 1.62.01 I believe). It won't work. You will need to upgrade through Windows XP. I was fortunate not to send my husband's Zen back to the stone age. However, I am joking as my Zen has the ancient, if not original, firmware of 1.40.01 or something (or .02). I have no intentions of tweaking with the firmware as there seems to be issues with the radio recording ability with other firmwares.
I have not found a battery from Creative Labs that will be suitable for the Zen Vision M. I have found that there are at least three brands and that when I have more information about the type of hard drives and the specific differences between our Zens, I will post that information.
Also, I am not sure how long these replacement batteries will last, or how long the charge is. I do know that the Camerson Sino is cheaper than the HQRP and should last longer as it is 1700mAh.