They may come back from the roots. Normally plants that die will die in the summer. In the winter they usually die back, but the roots will still be alive. They can come back from the roots one year, but if they die back two years or more in a row, their chances of making it get much smaller.

The die back or death may have been aggravated by previous stress that occurred last summer such as drought, sun/heat damage, poor soil, insect attack, too wet, etc.

If you scrape the branch slightly, there should be a very thin green layer under the bark and outside the wood. If this layer is dead, then that part of the branch is dead. You can start cutting back dead branches to improve the looks. However, I would wait until mid summer before writing death certificates.

Here is a link that might be useful: How to grow azaleas and their problems.

Thank you for the information as it was very helpful. I will check for a pulse.