This very thing happened to me.
I have a radio with a cigarette lighter power cord, in-line fuse very visible and easily accessible. But it also had another fuse I did not know about, which was inside the black plastic case that is the actual plug that plugs into the power source. Once when I thought my radio was dead (thought maybe lightning had hit it), it was actually that first hidden fuse had blown (the second visible fuse was still good). Luckily, I didn’t trash my radio. Found the hidden fuse using a VOM, replaced it, and radio worked fine.
One more note on replacing power source fuses. Pay attention to the fuse ratings. Replace with exactly same rated fuses only, no more, no less. On the radio I cited above, I first replaced the fuse with a lower rated fuse. Radio worked fine on low power (99% of the time), but then blew days later the few times I used a channel programmed for medium or high power. Again, thought the radio was bad, but finally figured out the fuse I was putting in had a too low rating for the radio to operate at med or high power, so it would blow every time (went through 4-5 fuses trying to figure it out).
But also and more importantly, don’t ever put in a higher rated fuse than what came with the radio, or what the manual calls for. Better to blow a few 25 cent fuses than a $150+ radio with a now voided warranty.
I hope my lesson(s) learned can help someone else.
Thomas
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EDIT: Corrected voltage ratings mentioned (thanks Lscott for pointing that out).