I think you;ll have to take it apart and have a look, make sure it is the heating element - it could be something simple like a thermal fuse etc
take it apart, power it on, check there's power going to the heating element
this place doesn't list dehydrators but looks to have a good selection of spares for other things made by the same people...
https://www.nisbets.co.uk/catering-appliances/spares-and-accessories/buffalo-spare-parts/_/a33-3I couldn't find any info about the heating element... but the whole thing is 800watts so you can bet the heating element itself is 800watts (fan power will be a couple of watts max)
800watts is more than I expected... I wonder if there's multiple heating elements inside it, so it can heat on low/medium/high etc. - this could be another point of failure :-o