If the battery of your FSH6 handheld spectrum analyzer cannot be charged, there may be several possible reasons as follows:
1. Aging of the battery: If the battery has been used for a period of time, it may be aging, causing the battery to not charge properly or maintain its power. If this is the cause of the problem, you need to replace the battery with a new one.
2. Charger failure: If the charger is damaged or malfunctions, the battery cannot be charged normally. You can try to use another charger for charging, or use a multimeter to test the output voltage and current of the charger to determine whether the charger is working properly.

3. Charging interface failure: If the charging interface of the spectrum analyzer is damaged or malfunctions, the battery will not be charged normally. You can check whether the charging port is clean, or try using another charging cable for charging.
4. Software problems: Sometimes, problems with the software of the spectrum analyzer will also cause the battery to fail to charge normally. You can try to restart the spectrum analyzer, or upgrade the software version to solve this problem.
If you have tried the above methods, but the problem is still not resolved, it is recommended that you contact the after-sales service center of the FSH6 handheld spectrum analyzer for repair or replacement

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