2007 toyota camry. my mechanic changed out the air conditioning system. he claims that the antitheft device is preventing it from starting. i called toyota

and Toyota said that changing out the air condtioning system would not
cause it to have to be reset. The battery was dead by the time that i had it
fixed and so was the battery in the key. I told him to pull the fuse but he
doesn't know what one it is.  I told him to change the battery in the key and
now he is claiming that he needs the manual to reset? I asked him reset
what? no response. i am very rural and had it towed there. I need my car
asap. Please tell me what to tell him what to do so he can understand it.
thank you