Apart from looking so crude: This device actually worked! I was able to re-flash the UEFI BIOS directly on the motherboard and the computer starts again! More important is though, that after that worked, there is no reason to NOT further play around with the BIOS anymore. Watch out for news or try it on your own. An interesting low-level world has forgotten to lock its gate 😉
The whole story: I faced a serious issue with my computer the other day, when it wasn’t booting any more and stuck on the BIOS logo screen. I tried DEL and the F* keys, but the system did not respond by any means. But I further noticed, that -within a certain time frame- the NUM lock key worked with a remarkable delay before the LED reacted.
I removed all components, even one of the two RAM sticks I have- still the same thing. Since the board had a dual bios, I tried to re-flesh the first from the second by holding the on switch for a few seconds. Although that seemed to work it did not fix the issue.
I removed and reinserted the bios battery and started bridging pins of the BIOS chip in order to erase it until I managed to get the computer in an even worse state in which it turned on and again off very quickly without showing anything on the screen.
I managed to destroy my BIOS and that used to be something for which you have send your board back to its manufacturer or buy a new one. But I was still not ready to give up on it and after some soldering and bug fixing I came up with a really crude solution, which I now want to share with you, because this thing looks so terrible, even though it worked 😀
Note: I also tried a direct connection with a more recent Raspberry Pi 3, but for that additional resistors would be required.