damn, okay here's the deal:

i used to drive a 1990 lexus es 250, well, it had the stock headunit that did not have a cd player, so i decided to change the headunit. i upgraded to a blaupunkt san jose. then after a year, i bought an rsx type S so i decided to swap the headunit back in. now, when i put the stock cassette headunit back into the lexus, i forgot the anti-theft 3 digit number that my friend and i input in the past year, now the headunit is not working because we tried five times and the darn thing won't come on.

Any suggestions, guys? Is there a way out of this? Or am I stuck with the task of buying an aftermarket headunit.

thank you.