I changed 2 battery cells and upon installing the battery I got the P3004 code. Googling showed anything from inverted to fuse to faulty wire harness. Looked in Dr Prius App that block number 3 was low voltage. Inspected block 3 and sure enough one of the bus bar nuys was not tight enough. Problem solved! P.S. when replacing abad cell, make sure to attach the temp sensor wires. Otherwise you will get more codes!
I hope you tightened those bus bar nuts with a 1/4" torque wrench. They should be tightened to 48 INCH lbf. Both too tight and too loose are not good.