There are certain things that can go wrong whenever you set up audio equipment. Let me give you some general advice for fixing some problems which will allow you to remedy the issue almost half the time. If the problem, however, is more involving that you might not have a choice but to involve a professional. Generally, I suggest purchase an extended warranty if the equipment is expensive. However, devices which don’t have any switches such as wireless routers usually last a long time and purchasing an extended warranty doesn’t make sense for these types of products.
However, if something does go wrong then the first thing I would recommend you check is the power supply. Some consumer devices come with an integrated power supply while others will include a wallwart which is connected to the main unit via a small plug. If you have the unit that comes with a separate wallwart that is usually quite straightforward to determine whether the power supply is okay. All you need is a voltmeter. Set the voltmeter to measure the voltage and then connect the test leads with the DC plaque while the wallwart is plugged into an outlet. They should be reading which is similar to the voltage which is printed on to the label of the power supply. If the voltage is significantly lower than the nominal voltage then the power supply has to be replaced. Generally you should purchase the power supply from the original manufacturer.
However, you can also purchase a power supply from another supplier as long as the plug is the same and the voltage is similar to the voltage of the original adapter. Also, pay attention to the current rating. The current rating of the new adapter must be at least as high as the one from the original adapter.
If your product has the power supply built-in then I would check whether the power fuse has been damaged. You can often remove the fuse from the product by opening a small lit which is located near where the power plug connects to the device. Then measure whether the fuse is blown. You can use the voltmeter to do this. If you don’t have a voltmeter then you can visually inspect the fuse. If the fuse is damaged then you should replace it with a similar fuse. After everything is OK then plug back in the product to see if the power has been restored.