Welcome to the forum. The following you tube video may help . It (eventually) shows how to access the interior fusebox , and the location of a fuse list. I think the radio fuse is in slot 14, the 5th slot from the top in the second column. It should be a 7.5 amp fuse. (dont be tempted to use a higher value fuse
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However fuses dont often blow for no reason. If its blown it may blow again immediately, or soon after, due to a short circuit in its live feed wiring or fault in the radio itself. Or someone might have blown the fuse whilst tinkering with the radio or wiring. If the fuse is still ok you may need to check the radio is earthed properly, and its live feed wire is actually receiving power. If not you may need to trace back systematically until you find the source of disconnection ,maybe a loose wire or poor connector. Or find whats causing a short circuit.
Fault finding is much easier using a digital multimeter . These can show if a live feed wire is indeed live and continuity of circuits to locate any break (eg detached or broken wire, poor connector,poor earth/ground return etc etc. ) You can also use this continuity function to double check whether a fuse that looks ok visually has actually blown. It happens sometimes. ( same with light bulbs)
Its worth buying a digital multimeter. (from about £7) You will find it useful for other things in the home and car. In time it will save you more than its purchase price. Eg devices such as mouse, remotes etc sometimes work after changing batteries just because of the disturbance to its electrical contacts. By checking their voltage with a multimeter I realised that over the years I had must have thrown away many perfectly serviceable aa and aaa batteries. At cost to my pocket and the environment
BTW is the radio still the honda original? If an aftermarket system has been fitted it may be wired to alternative power connections, different fuse slot, and may also have an 'in line' fuse in its live feed cable.
