2000 Citroen relay doesn't start

[m3mpower]

Hi everyone
this Citroen van relay, year 2000, was starting ok, then it stopped starting, then starts ok....etc
someone said the key has to be changed, the customer went to locksmith and bought a new key, after that, the van starts ok, but after one day, it doesn't start again,
there is a symbol of key flashing on dash
i posted the VIN on the pin to vin section but i was told there is no pin code for this vehicle
Can someone help please?

Thanks

[vuno01]

try to make immo off
to see if problem goes away

[m3mpower]

try to make immo off
to see if problem goes away
How?
immo off?
if there is no transponder code

[p309]

under the engine cooler there is some connectors try to cut them off, i had to do that on some of them, or the antenna for key reading is broken, there is immo system but you need red key to code yes?