Does the car start and run? The Toyota Camry Hybrid uses the MG1 (High Voltage Motor-Generator Assembly) to start the engine, so the engine can be started only with the high voltage system. For reverse "gear" the computer simply reverses the phase sequence to MG2, so the car is propelled only by electricity in reverse. However, if the car is throwing a code such as P0A80 (Replace hybrid battery pack) it can still be driven, the engine will just be running the whole time and the acceleration will be very awkward. Most acceleration from 0-10 or 20 mph is done with high voltage (through MG2). But some codes will not allow the car to even start.
The Toyota Camry Hybrid drivetrain is perhaps built around the Hybrid Synergy Drive system more than the engine. I do not recommend trying to drive the car without the Hybrid system in good working order. If the HV battery is only getting weak and unbalanced, I recommend the Prolong Battery Reconditioning system, which uses cycles of charging and balancing, then discharging, then charging and balancing, then discharging, then charging and balancing, etc., to rejuvenate the battery cells to proper performance. I am very happy with the results of this system on my 2007 Toyota Camry Hybrid.