How do you tell if fuse in etek 10709 is blown?

Simply open it....unscrew the battery cover and remove the two screws inside, then remove the two screws at the bottom under the flip out stand....separate the two parts and remove the fuse...inspect it to see if it is useable...a good fuse will have the wire inside intact...if not replace it with a .5amp 250v 20mm fuse.