Power button not working after replacing charging port and battery

the power button not working would imply it is not locking either. if this is the case, while removing the screen to start the replacements, you may have disconnected or damaged the power button flex.

if it is "not holding a charge whatsoever" it may be a bad or disconnected battery, or a short in the board caused by physical damage

"Doesnt recognize charging while plugged in" could be a signal failure from the new port, or an issue with the battery. There could also be physical damage to some of the components on the board causing this issue.