Help! CMOS resets at shutdown and, yes, the CMOS battery IS OK!

Hi
I have a Clevo (Metabox) m570u.
If I shut down the computer and leave the power cable plugged in, it will remember the time and bios settings.

If I sleep the computer, it's OK also.

BUT:
If I unplug the computer from the power and then shut down on battery, the CMOS will reset and get the following errors:
ERROR 0211 Check date and time
ERROR 0251 System CMOS checksum bad - Default configuration used.
The Audio DJ clock display will show the time as 80:17.

I HAVE INSTALLED a brand new CR2032 battery, which I tested with a multimeter as having 3.27v. The connection to the motherboard seems OK as I was able to detect 3.2v on the motherboard from the CMOS battery. My bios is 1.01.06
and KBC/EC 1.00.01T2

I have tried resetting the bios to default (which happens anyway...), tried removing the main computer battery, tried cleaning out dust in the fans.... The main battery although 4 years old seems OK - it measures at 16.8v and has enough juice to power the laptop for half an hour.

Anyway, I'm saying that I've tried the obvious, but I'd be happy with any advice as to possible solutions.

 

Ha HA!!!
Fixed. Joy oh joy.

Anyway, in case some poor sod has the same problem in the distant future:
My battery turned up with the positive and negative cables the wrong way round for the motherboard.
Looking at the computer from below with the hinges facing away from you (ie CMOS battery at bottom left) the cables should be as follows:
BLACK on LEFT
RED on RIGHT.

 

Considering the polarity was reversed you're lucky nothing serious happened.

 

I guess they must have put a diode in to idiot proof it. Lucky for me. Thanks to this site, I found the service manual and was able to see that the leads were back to front.
When I bought this computer second hand, it was actually MISSING the original battery and I'd been told it needed a new motherboard to fix the CMOS problem. So a $2 battery was quite a cheap fix...

 

just want a clear CMOS button
overclocking x7200......if the votage is not good and cant go in bios
have to tear it apart and remove that cr2032......................

 

Solder a little switch onto the positive lead of the CMOS battery.
Find a place to mount the switch.
Then drill a hole to allow you to press the switch with a paper clip?

Or:

Don't screw the computer back together after opening it, just sticky tape the bottom plate back on.