I think on my X459, it's 4 tries and your out........"Are all Kenwoods like this"?......I would hope all HU's were like that if the security is turned on! Why would you want a security system that, if you removed it from power, IE stealing it, could be turned back on by powering it up and punching in a new code? If that was the case, I know I'd never turn the security on because it would be worthless. Same as in the old days, if you stole a radio without a faceplate you couldn't get a faceplate unless you could prove ownership, unless you had a unreputable shop get it for you, "for a price"
Not to say anyone here is stealing radios and then trying to circumvent the security with an overide. That's the downfall of buying a car with a security system equipped HU, unless you get the security code, your going to be SOL when you need a new battery.
My suggestion if you ever buy a car with an aftermarket HU, and the security is turned on...it should tell you that when you power it on, I would make sure either the dealer had the security code, or they could get the security code for you before you purchased the car..........if not, I'd ask for a reduction in price, even if it was a 1000.00 unit.....because sooner or later...it's going to bite you!
Regards Sonny