Thanks for the input, dordale. It's definitely PW1 ("kindle" on the back, also the disassembly confirmed that). As having nothing to lose, I've took Kindle apart and gave it a thorough cleaning (mostly dust).
If anyone would like to take a look (please), here's the few pictures:
PW1 disassembled
Nothing seems out of ordinary to my untrained eye except a detail on the last two pics. You can see the corrosion on one of the connectors on the first one and the damage I've done after cleaning the corroded part on the second.
Here are the cropped details of the male part (unfortunately I don't know if everything's fine inside the female connector on the motherboard, just couldn't see anything):
Could this possibly be the source of the unresponsiveness?
(still no screen response after assembly)
I'd conclude this with the question from the end of my first post...
Thanks and regards,
Jim