That was my first guess. (Although im not sure what you mean re: strong/weak power adaptor )
I was initially using a Nintendo switch AC adaptor, which is rated at a switching (heh pun) 5V / 1.5A (pittance) and 15V / 2.6A. Of course the Devterm wouldn’t accept 15V, so that adaptor was both too powerful and too weak.
The official raspberry Pi 4 AC adaptor is rated at 5.1V / 3A. Significantly higher on both fronts. This is what I use for all my rpi4 devices, and never get the power low warning.
Now here’s the thing. I tried the Nintendo one first. No dice. Then I tried the rpi4 one. Also no dice. This was both with uncharged batteries, and no batteries inserted.
After I charged up batteries and put them in, it booted up.
After this initial boot, I tested both of my existing adaptors, WITHOUT batteries. You guessed it. They both worked. My guess is that for the first time boot, it requires power from batteries, whether it’s to activate the power management, or possibly a prohibition by the OS for the first time initial file system expansion to take place properly.
End of the day, my post was a reassurance to the OP and others that their LCD ribbon isn’t at fault, and to just try and get some batteries.