Duo500n Storage Heater - Fuse Blown?

Hi,

The 13A fuse in my off-peak spur had blown on my Duo500n heater while I was away for 2 weeks. I have replaced the spur/fuse and when I turn the heater back on the LED controls at the top just flash and I cant do anything. I have check the heating elements and all continuity points, everything seems fine as they are all taking a current. Could anyone help with this?

Note that this heater is only 2.5 years old and always on a very low setting, I'm surprised this has broke already...

Thanks