Clive - theres a very common fault on the 400 series module that you have in your Pulsar, the battery connection clips are soldered onto two wires inside the module, you can see these two connections if you look directly above the display and the circuit board, they go down and are soldered on. What happens is that when the batteries are changed the pressure on the battery springy connectors causes a slight movement and a dry joint appears on these connections causing a dead module or intermittent fault. It is quite annoying until you realise what the cause is because often the module works out of the watch and then goes dead when you put it in the case, and then it comes and goes as the dry joints open and close. I would think that this is where the fault lies if the watch starts and stops. It just needs a good scrape and clean and a resolder.
Here is a picture of a similar module, use a tiny screwdriver to push the connectors here and look for movement and dry joints in these areas, this is a very common fault causing dead or intermittent modules, the circuit board simply isnt getting any power from the battery connectors.
