2005 Nissan Xterra 2005 Nissan Xterra Electrical problems

I have an 05 Xterra. The vehicles battery died one night. After jumping, the vehicle would still not run normally. I replaced the battery and the vehicle started but the gauges did not function and the throttle was unresponsive. The vehicle would only idle. The mechanic replaced a battery cable saying it was corroded and that the battery was being charged at 16 volts but was unsure why at this point. He said there was a possibility that the main engine computer has been damaged. Has anyone heard of this or have any suggestions with how to proceed? Thank you.