You will need testing parts to use process of elimination and find out what is needed. Could be the battery (probably not cause for dim green light though), I/O board (liquid damage or worn charging port, try cleaning port) or I/O cable has liquid damaged pins. Check out the I/O cable and board, order the battery first (since that definitely has a fault), if there is still no charging light, order the I/O board (if the pins on the I/O cable look good).