Help - no heating or hot water

[nugeno9]

First time poster looking for help. I know nothing about boilers and have just moved into a new property.

This morning we got up and there was no hot water or heating. We have a Greenstar RI by Worcester Boiler (not a combi)

By the water tank we have a Frequency Receiver that is showing a flashing battery light on the screen.

Does anyone have any idea what i need to do? please put it in an idiots guide if at all possible.

Thanks for any help offered in advance.

cheers