Could you go to the Safe Mode or not?
A few other questions.
Do you have onboard/integrated video (embedded chip) or discrete graphic card?
Do you have Dell Factory Image Restore? Using this option (if you have small partition, about 10 GB or less on your OS drive) will restore PC to OS configuration as shipped, use it as last resort, everything will be wiped out.
Follow
http://downloads.dell.com/Manuals/all-products/esuprt_desktop/esuprt_optiplex_desktop/optiplex-360_setup%20guide_en-us.pdf page 46
I've also removed the battery, waited a couple seconds, put it back in and still no luck
When removing battery please follow this: turn off PC, disconnect from power, unplug, press and hold power button for at least 20-30 seconds, remove battery for at least 30 minutes, as soon as battery removed, repeat power button hold, after at least 30 minutes place battery back and put back PC - this is the correct procedure. After this go to BIOS (F2), next go to
Since you are communicating with us, do you have another PC or laptop, if PC, do you have space for another hard drive there, if not sure, please provide your secondary PC model.
If all attempts fail and you can not attach your fallen PC hard drive to anything, you might have to purchase a USB connector with SATA port (if you don't have Factory Restore) to wipe your hard drive externally, which cost around $20 plus shipping. But first try correct CMOS battery removal.