As far as I can tell, it's not easy to completely brick a Dingoo, as there are recovery methods available.
The first & most simple would be, if you have an a320.hxf (update) file on the root of your Dingoo's internal memory, reboot the Dingoo while holding DOWN on the dpad. This should start the updater, which will reinstall the firmware.
If you don't have the a320.hxf on the root of your Dingoo's internal memory, you can follow some of the steps in my guide for flashing custom firmwares, as it's a pretty good guide for unbricking a Dingoo too - http://boards.dingoonity.org/dingoo-hacks/guide-flashing-custom-firmwares-to-your-dingoo/
Get the file package that I've linked at the top of the post, and then follow from Accessing flashing mode with your Dingoo
. Instead of selecting a modified/custom firmware, you will need to get an unmodified firmware. As this will be flashed with the firmware flasher, you should be able to use any firmware version.
Also note the red text at the top of the post, any files that you have on the Dingoo internal flash will be lost.
It would probably be useful to know which LCD module you have, but as you can't boot into the Dingoo firmware, there is no easy way of finding out. I think the best way to tell is, if your Dingoo was bought after August 2009, then there is a good chance that you have an ILI9331 LCD module, so select the corresponding boot file for that.
I hope that helps, let me know how you get on!