I have exactly the same problem!
The Raspberry 3B+ does not boot at all, the green LED is not flashing, the red on is (as usual) lit.
So I expected that the Raspberry has died…..
It is, however, alive and kicking! I have downloaded the Raspberry OS (buster) and it works like a charm, so the Raspberry is OK.
I also would like to know what is going wrong…..
UPDATE: I have created a new SD image after reformatting the card, and now it is working!
Probably the SD card was corrupt, so the problem has been resolved.
Maybe you can retry the installation with another SD card.
At least, this was helpful in my situation…
Regards, Tom
