If you are having trouble untwisting the harness straps, we recommend referring to your G5 Infant Car Seat and Base manual HERE to see photos that may guide you through this process.
Detach the harness straps from the splitter plates and untwist them by pulling the harness straps through the front of the car seat. Make sure they are not twisted and re-thread them through the correct slots and re-attach them to the splitter plates. Also, before attaching them to the splitter plates, it is helpful to make sure that splitter plate strap is untwisted as well to ensure you can easily pull the adjuster strap through once you have reattached the harness straps to the splitter plates.