Hello Jacquesbth,
welcome to the Polycom Community.
The Polycom Support Page has clear instructions for any VVX 1500 Upgrade:
Before deploying UCS 5.2.0 or Later to VVX 1500 – Please carefully go through the instructions inTechnical Bulletin 695
If the above was not done the unit is now in a state that an End Customer cannot recover and a RMA is required.
Please ensure to provide some feedback if this reply has helped you so other users can profit from your experience.
Best Regards
Steffen Baier
Polycom Global Services
