HOME / KC901 serial VNA
In my experience of rechargeable batteries in general and lithium ones in particular, the batteries are likely to be dead.
The ones supplied in the device are "protected" ones which (usuaslly, especially in laptop batteries) switch themselves off permanently.
When one considers the cost of the KC901, this is probably a good thing as otherwise there is a risk of a lot of heat and damage within the device on next attempted use.
Open up the case (instructions on this bbs), take out the batteries and test/charge them externally.
Steve L, G7PSZ.
KC901 serial VNA