Key buttons will not operate locking system,i have changed battery but still no good.use master key,gets me into the car but alarm goes off and also when i attempt to drive it.

I have the same problem kinda. Lost my master key and sent my ecu off with a home made 2 button key to program immobiliser. This key works to start the engin and drive but I cannot get the key to program with the alarm and locking system. You can try the following steps as may work for you.

I can get my car into programming mode after step 1 but step 2 does not work for me. The locks do not go off at all, not once or twice. Battery in remote key is fine as LCD lights red.

Can anyone help please?

Toyota celica 2000 - 2005 remote keyless entry programming guide
STEP 1
1. Key out of the ignition. Open the drivers door , all other doors are closed . Driver door is unlocked

2. Perform these steps within 5 seconds
a. Insert the key into the ignition ( do not turn it ) take key out
b. Insert the key into the ignition ( do not turn it ) take key out

3. Perform these steps within 40 seconds
a. Close and then open the drivers door.
b. Close and then open the drivers door.
c. Insert the key into the ignition ( do not turn it ) and pull it out.

4. Perform these steps within 40 seconds
a. Close and then open the drivers door.
b. Close and then open the drivers door.
c. Close drivers door.
d. Insert the key into the ignition and leave it in the ignition.
Turn the ignition to on (as far as you can go without turning the engine over ), then back to off .
e. Remove the key from the ignition.

5. Within 3 seconds, the power door locks should lock then unlock automatically indicating successful entry into programming mode. Return to step 1 if the locks do not cycle at this point.

STEP 2 (Does not work for me)

6. Perform these steps within 40 seconds
a. Press the lock and unlock buttons on the transmitter simultaneously for 2 seconds
b. Immediately after letting go of the lock and unlock buttons, press the lock button by itself and hold for 2 seconds. Within 3 seconds, the door locks should lock then unlock once indicating successful programming. If the door locks cycle twice, repeat steps 6a and 6b as the remote was not accepted.

7. Open drivers door

Hope this works for you.
Hayley