Car engine temperature rising

I sent my car to a workshop to fix minor deformation in my front bumper, before this my car is working well and no issues at all.

To fix the bumper, the technicians need to remove my front bumper and lights. End of the day, when I collected the car, I tested and found out the my front lights are not working properly, so I told them to check what happened as its all working fine before they fix my bumper. They do checking of wiring and check my fuse and they said they found a blown switch which is very unusual.

I brought home the car, and after few miles of driving, I saw the temperature rising. So I immediately stop and check, I saw my reservoir full of water. Cooled down the engine and return to the shop.

To make the story short, the shop cannot find where the overheating is coming.

Done the following but still temperature is rising:
- Opened and clean entire radiator.
- Checked water pump.
- Checked thermostat.
- Checked engine for gasket issue.

I brought the car to another mechanic for second opinion, according to them, the radiator fan is a bit delayed when it open, usually, it will open once the temperature reach 50% or middle mark on the temperature gauge, but in my case it will go to around 55-60% before it starts running.

I can still use the car, but for short distances only and cannot go far as I am scared it will get overheated.

Let me reiterate, I do not have overheating, only after I sent for bumper repair and this started, could this possibly an electrical wiring issue that make my fan run late or slower than usual?

Thank you.