So I got the head unit from a 2nd gen xB because it has the RCA out. Once I plugged everything up, turned the key to position 3, the radio wouldn't turn on. The entire time I was doing the swap and running the RCA cable to the amp for my sub, the car was off. The keyless entry now doesn't work either, locking, unlocking, even the alarm. I tried putting the old radio back in, now it wont turn on either. I left the car off for a while, even unhooked the battery hoping the car would reset the ECU, but once I plugged it back in, still no luck with keyless, or radio, and now the car idles extremely low, like 500 rpm and barely keeps itself on. Did I blow a fuse somewhere? Do I just need to take it into the stealership? Any help is appreciated

 

found the problem, definitely blue a fuse. it was one of the blue 15 in the engine bay. once I swapped it with a good one everything worked as normal.