Traction battery and brakes

New member here. My 2002 Prius was diagnosed by dealer with the following codes. P0302-3, P3191, P3000, 3006, 3009, 3029, C1259, C1513, 1521-21. So, it looks like block 19 (P3029) voltage is sig lower than rest, and P3009 is likely voltage leak, and/or transaxle. My questions concern the difficulty in getting the car to go into reverse and the HV battery warning light seems to come on with brake warning light, ie the car may be driving okay—once it goes in reverse—then brake light and red triangle appear and power decreases, as if brakes are applied. While pulling codes, Toyota described this as left rear brake locked up and car not going into reverse. Question: is it likely that the hybrid battery and brake issue are related? Dealer would not further diagnose brakes before addressing battery. I removed left rear drum and brakes seem mech fine. Thx for any insight. I can get a new battery, uninstalled, for $1900+ tax but hesitant if other costly problems.