The service manuel is very helpful, we where able to restore the device to its working operation again.
Text excerpt from page 7 (click to view)
2.4.
2.4.1.
How to Replace the Lithium Battery
Replacement Procedure
1. Remove the MAIN PCB. (Refer to Disassembly Procedures.) 2. Remove the Lithium battery (Ref. No. �B9101� at foil side of MAIN PCB) and then replace it into new one.
NOTE: This Lithium battery is a critical component. (Type No.: ML421S/ZTE Manufactured by Matsushita Battery Industrial Co.,Ltd.) It must never be subjected to excessive heat or discharge. It must therefore only be fitted in requirement designed specifically for its use. Replacement batteries must be of same type and manufacture. They must be fitted in the same manner and location as the original battery, with the correct polarity contacts observed. Do not attempt to re-charge the old battery or re-use it for any other purpose. It should be disposed of in waste products destined for burial rather than incineration.
NOTE: Above caution is applicable for a battery pack which is for DMC-FS3 series, as well.
