Please explain how you isolate the PRSOV as the source of failure when you are not allowed to run the engine above idle??
Selecting the bleed off will close both HPSOV and PRSOV and doesn't troubleshoot anything bar the HPSOV closure function.
This can confirm a fault but only at switch level not at crossover where the fault could lie as at TOD.
Maybe the aircraft was commanding the valve closed but couldn't, it could be many a problem but untill you contact the aircraft no one will ever know!!!
Beeline out