A Raspberry Pi 3 Model B boot problem which happens after the very first installation of Raspbian

Question

Recently I experienced a breakdown of the SD card on a Raspberry Pi 3 B (no B+) I use as a courtesy PC for my nieces/nephews. Since I had two SDHC 8GB cards, I did not worry too much and

1. Downloaded the Raspberry Pi Imager for macOS.
2. Wrote Raspbian Buster with desktop on the SHDC card (a Micro SD Kingston).
3. Inserted the OS card in the Raspberry slot and installed Raspbian buster: to be sure of successful operation I rebooted the system a couple of times and it worked fine.

Then, just as a final proof-of-success, I powered off the Raspberry, turned off the power supply, waited a few minutes and then turned it on again: the system did not boot. I though it was a problem of the SDHC card therefore I repeated the same three steps, but the result was the same! So, thinking the board was damaged, I brought from my lab another Raspberry Pi 3 Model B (I never used it as I kept it as a spare part): however, after repeating the three steps above, I got the same results: the Raspberry does not boot after turning the power supply off.
After these test, I

1. Formatted again the SDHC cards and repeated the three steps above by downloading directly the Raspbian buster and writing it on the cards by using balenaEtcher: same result.
2. Tried to use an older Raspbian version, precisely the 2018-11-13-raspbian-stretch: same result.
3. Changed the power supply (I have a couple of original Raspberry +5V power supplies explicitly designed for the Pi 3 Model B): same result.

Now, my fateful final question is: why Raspbian does not boot after seemingly having been correctly installed?

Answer 1

This is the culprit:

This HDMI-to-VGA converter (the only object I have not changed during my many tests, and thanks to @Ingo for having opened my eyes on this) does not allow the automatic recognition of the monitor by the Raspberry. To solve the problem, I proceeded as described in this post. Precisely,

1. Since I use Raspbian, I accessed the boot partition of the SD card and then opened the config.txt file,
2. I uncommented the line hdmi_force_unplug=1 to force the HDMI mode and added the following ones.

hdmi_ignore_edid=0xa5000080
hdmi_drive=2
hdmi_group=2
hdmi_mode=35

3. Put the SD card with the modified config.txt file into the Raspberry.

And the monitor is perfectly driven since then.

Edit: further experiments with newer Raspberry Pi models. In these months I also experimented with new versions of the Raspberry, in order to enhance the performance of the courtesy PC but also to see if they inherit the same problem: precisely I used

• a Raspberry Pi 3 B+ and
• a Raspberry Pi 4 B with 4Gb RAM.

I was able to install Raspbian on them without having to do the above workaround in order to drive the same old SVGA LCD Monitors: therefore it seems that this problem exists only for Raspberry Pi 3 B or older models.