Minivator 950 stairlift stops woking?

It's had new batteries and a pcb board, it goes up about 3/4 of the way and stops and the fault code goes blank. If you leave it for a few seconds it will switch back on and it will go the rest of the way. When it's not in use it shows it's charging but after about 30 seconds the display goes blank. Anyone got any ideas
Steve, March 2018
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