In short, no. 6ya Experts are not expected to solve every problem they come across. In fact, some may not have solutions that can be implemented over the phone. And some may require more involved repair such as part replacement.
Your focus should be on accurately assessing the customer’s situation so you can offer insight as to what can be done to fix the problem. If an issue lends itself to a quick over the phone solution you should explain it to the customer.
A customer’s review of an Expert does not necessarily reflect whether or not you were able to solve the problem during the call. Offering helpful alternatives, being polite and showing interest will likely earn you a high rating even when you cannot solve the main problem.