Does the phone or charger heat up significantly? If so it could be overheating protection. If not the next step would be to replace the battery.

I had this problem too and came to no solution, If you charged it with a charger with more than a 5v output (any fast-chargers) like I did, then we may have the same problem. my initial theory was that the batteries couldn’t take the extra voltage and destroyed themselves but I have now taken It apart and wired a 5v cord directly to the motherboard and it did nothing so Im thinking the overvoltage to the battery caused the motherboard to be flooded with power and it shocked or arched or something, essentially it destroyed itself because of overvoltage. tldr, either replace the motherboard (which I can’t find a spare of anywhere online without buying a used one off ebay and running the risk of it having the same problem.) or scrap it for parts.