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I recieved a BIOS update from A05 to A07 this morning, when installed it told me the system had to be restarted, so i did and then the computer shutdown just like after most updates, but never came back on. called dell tech support and they are saying since i didn't unplug usb peripherals that it fried the motherboard, anyone else heard of this, anyways they are sending me a new motherboard and say it will fix the problem. any feedback would be appreciated

You must always follow the BIOS instructions exactly... and what you described is posted for the E510. The safe way is to flash the BIOS from a floppy DOS disk, as that prevents this problem usually... but many E510 machines do not have a floppy drive.
Here is what the Dell site says for the E510:
"NOTE: Shut down all other applications prior to running the BIOS update utility. The update utility reboots your system in order to get the new BIOS loaded.
Run the BIOS update utility from Windows environment
1. Double click the Icon on your desktop labeled D5150A07.EXE.
The Dell BIOS Flash window appears
2. Click the Continue button.
The message Pressing OK will close all applications, shut down Windows,
Flash the BIOS, then reboot. appears.
3. Click the OK button.
The system will restart and the BIOS Flash will be completed.
Run the BIOS update utility from DOS environment (Non-Windows users)"

If you are under warranty, or if you followed the above instructions, they should not charge you the $150 for the new motherboard.

there were no instructions, it just downloaded with a few other updates and i clicked continue to install them and thats when it shutdown,

Funny, my review of the Dell site found the instructions for the Dell E510 prominently displayed.
I hope you have not buggered up your motherboard.
You might want to call Dell techsupport to see if you can remove and reinstall the BIOS.