What does a hybrid inverter cost

What is your question?

The ck hybrid notification comes on for a few days and then goes off. It seems to come on and sometimes cuts the engine off, when I 1st back up. The large battery system was changed out a few mo back. That seems to be working fine, charging up and the gas millage is back to normal. Dealer ship thinks it may be the inverter their cost to replace $6500.00. What is your opinion?