Don't Complicate It - It is the batteries

A friend of mine's watch stopped, I said it was the battery.  She told it to a commercial chain watch repairs shop, and they said they would have a look as it maybe more than just the battery as there was charge on the battery, and ultimately concluded it was just the battery.

Then one of our change over units did not work, we pointed straight at the battery, but Paul said the voltage was fine.  I asked about the date stamp, and Paul didn't even check.  As expected, it was the battery, the voltage is fine doesn't mean it can supply the essential current.

Don't complicate things, battery operated system faulty always check and replace the battery first!