@jamesmarsh12177 first check your charger. Make sure it has proper output. Then check your charging cable. Check to make sure the connectors are not bend etc. After that, check the charging port. Clean it of any debris etc, use a few puffs of air to clean it out. If none of this works, get a USB ammeter and see if your phone draws any amperage from the charger.
Commonly a No Power situation is related to either the charging board, a shorted battery or a torn flex that comes from the daughter board to the main circuit board. Check/replace those. Then check the voltage on your battery connector with the phone plugged in and without.
To replace the battery, use this guide [guide|146769|Poco X3 Pro Battery Replacement|new_window=true] For the rest use [link|https://www.youtube.com/watch?v=1Tkmqn2fFMg|this video|new_window=true] Let us know what you find out.