How to resolve advisor/student relationship issues?

Thanks for your guidance. Here is an update that need some insight.

My son applied for PhD program in many schools. No one offer an admission. He is frustrated after putting effort and submitting reference etc. He find hard to digest this setback.

We do not have an idea, what went wrong here. Who is able to review and provide assessment/diagnosis?

You know schools are closed for this pandemic and all facing difficult situation.

As he graduate in May 2020, he will be in academic limbo.

No one expected this when he applied to programs.

What are the next course of actions available to him?

Thanks for your guidance/insight.