Yeah removing the battery wouldn't work since its not a bios issue.
REMEDY FOR STARTUP:
Go to Start, Settings, Control Panel, System.
Then go to the Advanced tab, and where it says Startup and Recovery, hit settings.
Now press the Edit button.
Your system will be set up something like this:
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windo ws 2000" /fastdetect /NoExecute=OptIn
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Windo ws 2000" /fastdetect
All you'd have to do is remove the second or first one there that you don't need.
You'd then simply have to change the default one at the top where it says "partition(x)" (x = the partition number), to the one you have left, e.g 2.
Then save it to stop this coming up again.
If you don't know which one you formatted and so if you pressed it, windows would fail to load, rename both of them in the "" brackets so you'd know which is which, and restart and check which one you go on. Then go back to that and delete the appropiate one.
As for your cd rom drive not working, open up the computer and check it is installed correctly. That the power cable is in all the way, and that the IDE cable going into it is secured, and the same for the connection on the motherboard it goes to (usually IDE1).
Does it recognise it in bios though when its booting up and finding the drives? if it does, at least you know it is connected and it is windows fault, though I dont see how it can be since you've reformatted.
If it doesn't recognise it, just check the option above for any loose connections and hopefully you'll have a working system again!
I hope this helps