Master Cylinder Access and Bleed

[eman2024]

hi all

vehicle 2013 XC60

my brake pedal is dropping to the floor. i bled all the lines, several times. lets just say the fluid is CLEAN and flushed.
ive bled the lines with engine off, and on. the brakes are firming up but still are spongy when i drive it later.

i think i want to bleed the two lines in the master cylinder before replacing it. i may have gotten air into it when bleeding the brakes as i got several low brake fluid warnings and i may have pressed to hard on the brake a few times. oops.

the ECM elec control module is right next to the master cylinder. see attached image

i want to remove the ECM temporarily and safely to get to the master cylinder.

this video shows how to remove the ECM https://youtu.be/pcFlWmKhz1k?si=TzsFWPShwQly_Kib

does it matter if the battery is still connected? how long can this ECM remain disconnected?

im being cautious, but would like to know how to interact with the ECM properly.

[eman2024]

issue has been resolved. disconnected the battery and then the ECM.
bled the Master and the brakes now work.