Could you please advise the model of dishwasher and also what lights are shown on the control panel.
Once you select a cycle which lights are showing and do any flash?
I just want to clarify based on comments made earlier on, when you set it to option 1, does it start to fill up and release the soap\tablet (as you hinted that it may be starting to fill up but not dissolving the tablet)
This sounds like an inlet valve or flow sensor fault, which will require an engineer to attend to strip the unit down and check both the valve and sensor and then fit the replacement part.
The parts are around £30-50, if you provide me with your postcode I can recommend a suitable engineer in your area.
Due to the complexity of the small appliance the local engineers we would normally recommend do not touch these models, however Repair and Protect will come and repair the unit for £174 and that then gives it a further 1 year warranty, they can be contacted on 0808(###) ###-####and selecting option 1.
Alternatively you can use Go Assist on 0800 8654 111 and select option 1, they charge £120 for a fix only service.
Both companies have a no fix no fee policy.