Complex battery issue

[onyxvu]

Hi guys! I really did search before posting so if this is covered somewhere else i'm sorry. i'm repairing a model a1103 for a friend. there is no sign of power from the mini. the cord and power supply has been tested on another mini and works fine. i opened it up and found the pram battery is totally dead. i thought this was weird but moved on. i replaced the battery with a lithium cr2032 as descibed by Apple- nothing. so i rechecked the new battery- 2.3 volts. Huh, bum battery- got another and checked it first. 3.12 volts. plugged it in and literally watched the voltage drop like seconds on a clock. any ideas???