2003 S-10 - $700 (Elizabethtown)

2003 S-10 ZR2 3 door, put a good transmission in it, got it back together and security light and wouldn’t let it start,I’ve tried quite a few a bit of Google relearn methods and haven’t had any luck , I drove the truck when I bought it but it 3rd gear or passing gear, pretty good body, I’m the second owner, the guy I bought it from let it sit for 8 or 10 yrs before I got it,planning to get the trans fixed but never had the money,motor has 178000 miles on it, would like to get $700 out of it, since I bought the trans and put it in, I drove the blazer home , $700 OBO it’s a 4x4