I solved the problem!!
After searching around the t'internet I found a video that not only explained what was happening. But why it was happening, and how to fix it.
The video is here:
https://www.youtube.com/watch?v=oCKCGFnGdm0But in my words it seems it is caused by overcharging the batteries causing memory loss.
According to the video when a battery keeps getting overcharged it loses the memory of how much power it has. So even though the battery was showing fully charged the memory thought it didn't have much charge so kept "blanking out".
The fix is to buy another rechargeable battery and not over charge them. He said its a common problem because most people finish using the phone and put it back on the charger.
So I bought new batteries and the phone started working again. During my tests a 3rd phone stopped working. But this time I had bought an extra set of batteries (got a 2 pack of 2), so I changed the batteries over and it started working again.
So the moral of the story is to stop putting the phone on the charger as much as probably most of us do.