last year around September my rer 730N got stuck in a boot loop. I remember changing my spark plug around that time. last week en it was pretty humid, and going down the highway my replacement radio got to boot loop like the original radios. At 350$ a pop or more, I'm more looking in to finding the problem. i,m wondering if I haven't isolated the spark plug correctly if it can blow the radio. All the fuse seem to be ok. Any idea.