Peugeot Boxer, I don't go to Massssssss

Greetings to the entire community, my question is what to do with a 2000 Peugeot Boxer 1.9 Diesel. The warning light on the dashboard has stayed on.
It's key-shaped and says CODE, so it won't start. They're charging me a lot to repair it (280,000 pesos). They told me they have to reprogram the computer and then find the problem and a bunch of other details... I talked to a guy who has a Peugeot parts yard; he's charging me half price to eliminate the locking system by changing a fuel pump sensor and making an electrical modification for the fuel flow... (since I didn't have the money, I did the work myself). I changed the sensor for one with the opposite action (the one I had, when I connected the power, the plunger popped out, and the one I replaced it with, the plunger goes in). I connected it and tried to start it, and... it won't start... hahaha. I don't know how to disconnect the lock on the back of the pump where 3 wires connect. If someone could help me with my problem, it would be great, since I've been riding my motorcycle for 2 weeks and I'm... More of a cold than shit.....A big hug and greetings to the whole community(Sincerely, Luis Acuña