- Can a bad battery keep a Fuze from working even when it’s plugged into a power source (with or without the data connection)?
Probably, as a safety feature in case of a shorted battery, the system may not allow charging if it detects a short. I’m guessing that it may not let the player power up under some battery detected fault conditions.
- If one wants to take a battery from one Fuze and use it on another, where does one make the separation between the battery and the circuit board?
Unsolder the red,black and blue wires at the top edge of the main board. Do one at a time and DO NOT allow the bare lead ends to short against each other. If the battery has a charge and the leads are shorted, it could start on fire or explode!
- Is there any way to test whether a Fuze battery is good while it’s connected to a circuit board that’s bad or of unknown condition?
Not really. To test a battery properly it needs to be connected to a known good player board. It can then be verified if it fully charges in a reasonable amount of time, holds a full charge without self draining rapidly and that it can sustain power to the player for the rated amount of time for discharge.
- Is there a way to test such a battery when it’s not connected to anything?
You can only test for a voltage level. This will not prove much of anything. You need to dynamic test as explained above.
I have a multimeter but no fancy equipment.