OK, button push & no led
You already know to push 1-2 sec, not a quick stab
do, in order
Hard power off,, ~7-8 s, then 1 s start
no led? then
Hard reset,, 20-25s, then 1s start
no led? try another card
preferably with emmc removed, or at least disabled, but better removed
And, you know charging is working OK, well at least as good as it gets
Explanation: AFAIK, since pbp has a battery, a "bad" uboot can persist, even when card is gone
Note which specific card/distro does this (hard lock), let us know, then wipe it, never use that specific distro again
You already know to push 1-2 sec, not a quick stab
do, in order
Hard power off,, ~7-8 s, then 1 s start
no led? then
Hard reset,, 20-25s, then 1s start
no led? try another card
preferably with emmc removed, or at least disabled, but better removed
And, you know charging is working OK, well at least as good as it gets
Explanation: AFAIK, since pbp has a battery, a "bad" uboot can persist, even when card is gone
Note which specific card/distro does this (hard lock), let us know, then wipe it, never use that specific distro again