Power Pilot frozen, shows 888

[Greg]

My PP worked fine until yesterday. I switched it on the usual way to start my workout and it displayed eights all over the screen ("full display", like in reset mode). It has been frozen in this state ever since. The only way to "switch" it off is to take out the batteries. As soon as I put them back in again, 888 all over the screen (no need to switch it on). 

Any solutions to this issue?