ahhh hahaha yes ive had this happen i was playing along then dooop all the numbers were gone just the stinger remained illuminated....
i had it wired in with quick disconnects so that i could easly remove it from the top of my dash this is in a 00 crown vic body style, after the voltage meter did this a few times randomly, (each time i had to disconnect it and re plug it in and it worked which would mean take my entire dash pannels out which are a pain in the ass in the dark!) back o track to, i proceeded to rip it the fuck out pissed off, eventually i put it back in where my clock goes and it has been working like a champ everytime
put it on a switch, that switches the power not the ground, shit or both, so you can dissconnect it and reconnect it easily
and if that doesnt work sorry man, just hit it with a hammer it will work and 20 dollars later ull have a new one
hope that helps