If you're not getting video and you're using the onboard video, you can try putting a video card in. If you're able to get the first post screen you can press End to launch Qflash to reflash. If you're using 4GB RAM you can try taking some out. If you can't get video and can't get it to boot to a floppy then you may have to RMA the motherboard. Sorry you had this problem. The only module that was moved was epa to end so overall was a relatively safe mod to try. It may have been a bad flash.
You can probably rearm or do the safe mode thing. I dont think it will hurt to flash, then go into the OS and remove the bootloader. the cert and serial may already be installed, Am I right??