Automatic Emergency Braking problems of the 2007 Nissan Murano

Recently my 2007 Nissan Murano was dragging a little on slow speeds. I checked the wheels and found the driver's side rear brake had more brake dust then the other side. I pulled the wheels and found that the brake caliper was froze. I bought two "new" calipers and rotors and replaced them. I then used an air driven suction device to replace all the fluid in the system and bleed the air out of the system. When I started it up the brake pedal was very spongy so I brought to the local tire kingdom about 1/2 mile away and let them bleed it out. They stated that the master cylinder was now no good. I purchased a "new" master cylinder installed it, and re-bleed the system. The pedal was still dangerously spongy and low so on 06/14/202i the vehicle to the local Nissan dealer. After a few days they stated that the "abs brake actuator" was not functioning. I questioned why the abs warning light didn't come on and they didn't know. The dealer said the part was no longer available new so hey offered to get one from lkq scrap yard for $780. 00 and for $220. 00 more it would be covered for a year. I looked into the issue and found that the 2009 Murano's were recalled for this issue, so I inquired what year was the part coming out of. They didn't know so I got one on my own from the exact same vehicle and brought to them to install. A few days later they stated that the new "master cylinder" was defective. I went back to nappa auto and bought another one and gave to them to install and re-bleed the system. My question is a vehicle with an abs warning light a brake system warning light and even just a engine check light never came on, why not? the dealer has no answer for me and I am concerned that this will happen again and possibly at a higher rate of speed. Can you investigate this incident for me? thank you for your time and consideration.