immobiliser engaging Toyota camry altise 2003

Hi, I hope someone can help me with this. basic problem:
master keys not being recognised (?) by car and immobiliser kicks in.

background. my car was broken into after buying another car. they destroyed the lock basically but didn't get anywhere with it. it was at my ex's place so ended up hot wiring it and drove it home with the master key in the transponder. my full comp insurance had lapsed unfortunately by mistake so I decided to install a push start system in it to circumvent cost of buying new lock and keys and it had been sitting in the garage (friends place) for quite a while. first 1 key wouldn't work with it anymore after battery had gone flat basically (?). then second key wouldn't work anymore a couple months later. I thought it was the push start system that had a immobiliser in it so ripped it out to isolate the problem. I rang Toyota and they said to bring it in as they didn't know either. I want to try fix it myself as I want to sell this car and still actually get money for it as I had that calculated in with buying the new car.

Thanks a lot

anyone please?

I read somewhere that you can buy a bypasser too? not sure where to look for that tho..

Thanks peeps

The car won't start and there is a flashing light on the instrument panel indicating a transponder problem?
Do you have any transponder chipped keys that still start the engine?
There are transponder bypass modules available for the U.S. 2003 Camry ( assuming yours is the same system ) like the Fortin Key-Override-All, but they need one working key to program the module. Here is a link to their WEB site for more info :
     https://fortin.ca/en/vehicles/toyota/camry/2003/

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