[Sapote]

I would also open the bleeder screw a little to let the pressure out to see if the coolant in the ET drops or not, if it does drop, there is probably air in the system, if there is, go ahead and re bleed

Don't do this. As soon as the bleeder is opened coolant will flow back into the ET and overfilled it, then you have to bleed again.

 

[Sapote]

Yesterday I filled the coolant after having the car apart for some time and as soon as I turned the ignition on the low coolant level light came on

with cold engine, open the ET cap and see if the coolant level is between MIN and MAX. If yes then check the sensor connection or try to swap out with the windshield tank sensor.