radio will not power up after a battery change

I have checked both fuses and they are good. I also checked to make sure I am getting power to the fuses and I am. Everything else is working. The clock. cig lighter, all lights, and gauges. This has happened before but I can't remember what I did to fix it. I

ok,so you TESTED both fuses with a test light and you have power to the fuses on one side,but do you have power on the other side of the fuses going out,key on? if fuses test good,try and wiggle the wire(s) coming out of the fuse box,see if that does anything.I would test all fuses,takes less than 5 minutes with a test light.

Yes I tested all fuses and I have power on both sides of fuses. I think it has something to do with the security on the radio.

ok,but if you have power on the radio fuse on both sides (the fuse that's hot at all times),then you should have power on that wire from the fuse box going to the radio connection with the key off?

There is a box under the radio that has a harness going in and one going out to the radio. The harness going in has two wires that are hot all the time and one that is hot only when the key is on. The other wires are for speakers. I am still not getting power through the box and to the radio. I took the harness from the box to the radio off and checked the wires with a meter and they are good. I do not know what this box is for unless it has something to do with the security system on the radio.