This "no other codes" part bugs me. P3000 is a code from the hybrid vehicle control ECU (up in the instrument panel area) and typically means you have some more-specific code from the battery ECU (inside the battery enclosure) telling you what's what. I would usually interpret this as meaning your code-scanning tool/app is showing you HV control ECU codes but not battery ECU codes. On the other hand, you've got a tool that shows you battery block voltages, which are also from the battery ECU, so it's not completely unable to communicate with the battery ECU. Odd. Can you at least get the INF code for the P3000 in the HV control ECU? That would still be a little better than shooting in the dark.