Perhaps the problem is solved already, however there is one simple solution that is always worth to try.
The problem with BIOS manufacturers is that their versions may assign different memory allocations to the BIOS memory, and then even a correctly installed, new and perfect BIOS version can cause these problems.
I have seen this many times with older machines, where the BIOS flashing took place correctly, however the system fails to boot due to messed up bios settings which are stored in RAM. This memory retains its information with a small battery, which is also responsible for the real time clock of your PC.
You can easily solve the problem by removing the Lithium battery on the main board, then wait a few minutes, then put in the battery and reboot.
Then the BIOS will detect that there are no BIOS settings, and use some default settings, one of which is (surprise!!!) the monitor.
It will tell you that some settings are erratic, but at least you are now able to press DEL to enter BIOS setup.
There you choose either "Load default fail safe" or "Load optimal settings". The latter will work most of the time. Save these settings and reboot and see whether your attempts were successful. I've seen this type of boot failure on several machines and in case of bios update failure, this is the solution.
If it does not work at once, try to keep out the battery longer, and short-circuit the + and - pins of the battery socket.
When you manage to get some life back into your PC, then don't forget to check that you indeed flashed the BIOS version that belongs to your motherboard. Maybe you flashed just a slightly different version. If so, find the correct BIOS version even if your PC seems to work after following above steps.
After flashing the BIOS correctly, surely you will need to do the same trick with the on-board battery.
Succes,
Willem