@celiacamacho there should be no reason to change the battery and the alternator three times. Measure the voltage output on your alternator. Get a multimeter and set it to DC voltage. Place the Red probe on the positive post o f your battery and the Black probe on the negative post. You should get ~12V on your battery. Now start your vehicle. The voltage should increase to 13.5V to 14.5V. Once it does that, try to place a load on your charging system. Turn your headlights on as well as your fan at high etc. The voltage may drop slightly at first but it should come right back up to the 13.v-14.5V. If not, then you know that your battery doesn't get the power from the alternator.
Next you should check the alternator output directly on the alternator. For that, connect your multimeter Red probe to the B+post on your alternator and the Black probe to ground. Now start the engine if it is not already running. You should see an output of around 13.5V to 14.5V. If you do not have this voltage, your alternator has failed.
You do have to be careful anytime your test anything on a running engines. Keep your hands, hair and loose fitting clothing away from any rotating parts. You do not want to lose a finger or worse by getting pulled into the engine. Also make sure you have the emergency brake set and I prefer some chocks to prevent accidentally moving of the vehicle.
If your alternator has the proper voltage but it does not get to your battery, you are either having a wiring problem or a fuse problem Check to make sure all the wires are properly connected, check for corrosion as well. Furthermore you have to have a good round going to the engine block. Again, check for loose, missing or corroded wires. To check for the alternator main fuse, use something like this video
As for your Radio, once the charging system has been fixed, check the fuses for the radio. Make sure that those are ok. Your radio may even have an inline fuse, so make sure you check that as well.
While you work on your car take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has the same problem as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.
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