Car wont start on first 2 cranks,security light stays on now.

If the security light is off then its not an immobilizer issue. Hence the no difference with key relearn.

Does it crank (starter engages) but doesn't run or no crank?

Year make and model?

When you say won't start do you mean it cranks n won't start or do you mean you turn the key all the way n won't crank I can help you but your question need to be more specifies good luck

check that it has power at the coil ,crank sensor,etc. with a test light when cranking it over.

Could be the neutral safety switch, or the security system, or a wiring problem.
If the security light stays on, you may have a problem with the VATS system reading the chip in the key. Try a spare key.
If it cranks in neutral and not in park, the neutral safety switch may be faulty.

Is the security light staying on ?
Usually the engine will not crank and you have no power to the fuel pump if the security system is disabling the car.
No injector pulse but spark would point to the computer since both use input from the crank and cam sensors.

I am sorry but this model is not sold in the US so we have no tech data on it to give you.

Does it start and die after 1-2 seconds or just cranks and never fires? Did it run before you installed the computer or are you trying to cure a no start problem?

try locking and unlocking the drivers door with the key. [sometimes if you reach to un lock door through window it it sets off security]

Body Control Module (BCM) on both counts. Find a shop in your town that specializes in electrical systems to test it. Beware, these can be intermittent problems, so make sure they keep it until the car does what you have observed. Expect to spend about $450 for the replacment. Dealers quoted me between $700 and $1,100 for the same repair. By the way, a new BCM will probably only last you about 12 months.

how to get the security light off and to get my car off security so it will stay running