Thetford 200CWE electric flush toilet.
The flush button is on a removable bezel which is held by two plastic 'posts' and some non setting mastic sealer...prise off carefully with a broad blade screwdriver.
underneath the bezel is a plastic grid held with 4 screws...2 x rear..2 x front...ignore the center ones, they hold the plastic posts.
when removed look to the left, you will see the white filter, follow the pipe down and you will find the pump.
CAREFULLY unclip the pump amd hoses, one hose directly below the filter and one at the opposite side to the bowl outlet.
lift out the pump, filter and hoses.
Look underneath the pump, you will see a red wheel with ribs...this is the impellor and chances are it wont turn.
use a small screwdriver to gently turn the impellor, it gets easier as you turn it.
i stood it in a small glass of vinegar for half an hour to break up any limescale...seemed to help.
Once it turns freely replace the blown fuse.
its a 3amp but not having one i fitted a 5amp.
hold a bit of rag over the pump outlet and press the flush button.
If the fuse still blows you either have a duff pump or a wiring fault assuming the impellor is free to spin.
reassemble in reverse order.