lost power brakes...?
 

I have an 04 T4R sport edition, 109k miles on it, and just 3 days ago I heard a terrible grinding sound from my brakes on the back passenger side rotor. From driving it a few more miles, it started grinding when i wouldn't even be braking. After driving a bit more, i threw some snow at it to see how hot it was, and it started to make the snow melt instantly and steam. I didn't throw too much snow at it but just a tad bit!! So i let the car sit for a little, only driving the car if i REALLLYYYYYY needed too. My mom needed me to pick her up from work, so on my way down, i drove about 20 miles and emergency/parking brake light turned on, so at the next light i put the car in park, and pressed on my foot brake thinking maybe some ice built up and started tugging at my e-brake cable make the light appear. The sign didn't go away, after releasing the e-brake, but as i drove away i didn't hear any grinding or anything, and i drove a half mile more to my mom's work. When i pulled up the VSC TRAC, VSC OFF, and ABS lights then came on INCLUDING the emergency brake light. I decided i had to at least try and drive it home, but then a loud buzzing sound came on, and i lost my power brakes completely, i had to go home slowly as well as slow down earlier because i couldn't stop like i used to be able to. So a few days go by when i don't drive the car, i start it and i still have all 4 lights, and the buzzing sound, without any real stopping power, but i had parts delivered to my house, i changed out the bad rotor and brake pads (if you could even call them brake pads anymore), and then i wasn't able to break free the driver side rear rotor screws because of corrosion, and i do NOT plan to drive with my car in this condition, but would a bad rotor and almost no brake pads really throw off the car's sensors that much where i lose my traction control and abs brakes? or did something else go wrong and it was just coincidental that it all went bad as my rotor was bad? any help/comments are greatly appreciated!!