2015 Silverado 2500 brakes

[hayespainting]

Could use some help!! 
got a 2015 Silverado 2500 few weeks back ABS started going crazy brake was sticking, so took it to dealership they swapped ABS module then later said contaminated brake fluid and wanted 4500 

to do the brakes!!!

I had replaced front calipers within the year and decided to warranty them and tackle this on my own!!

now ive flushed the fluid replaced master cylinder, booster 4 calipers 4 rubber lines been pressure bled and vacuum bled also did ABS bleed

can not get a firm brake!! It’s very spongy And slow to return!!

 

bench bled master cylinder later I thought I may have damaged it so I replaced it again and also replaced the booster again too!! 
 

my brake light is on and traction control as well.. any hep would be greatly appreciated!!