Initially, pls confirm if your unit is a PV-GD320 or a PV-GS320.
Offhand, I understand that the PV-GS320 has provision for directly connecting an adapter making the unit operational even without a battery pack. If the replacement charger matches the specs of the Panasonic, then try without the battery.
If even with direct power, the camera will not turn on, then the internal electronics would have to be attended to as you posted.
Alternately, you may try to disassemble the cassette holder but there is the risk of damaging the mechanism and most likely even the tape. Thios would require the use of a set of jeweler's screwdriver to effect the disassembly.
Hope that this be of initial help/idea. Good luck and thank you for using JustAnswer.
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