Rotor rub is driving me crazy, can't fix it
So i bought this used, modified kent trouvaille on Facebook marketplace with generic IIIPRO E4 4 piston brakes. For the first couple of months the bike ran really smooth with no issues. I then started experiencing rotor rub in the rear due to a warped rotor.
So I took it upon myself to order new pads, a new rotor , and a bleed kit. Im not super competent yet but im mechanically inclined and I want to learn. Well I attempted the bleed which was a disaster as none of the adapters were labeled. I thought I bled it properly but alas my brakes had no pressure and I couldnt figure it out so I took the new rotor, pads, and my bike to a shop to have them do the bleed and install the new parts.
So I get my bike back and im having rotor rub that I cannot for the life of me fix. Ive tried aligning the caliper by hand for hours. Ive thoroughly cleaned, massaged, and lubed all 4 pistons. Ive tried the trick where you slightly loosen the caliper bolts, hold the brake lever and tighten. Nothing. Ive spend hours messing with it and a couple of times i actually got really close BUT the final synch down of the caliper bolts always pull the caliper out of alignment which I cannot prevent by physically pulling the caliper the opposite way. I've tried and tried and right when I feel like I fixed it that final tightening of those 2 damn bolts makes it rub again. And yes I am alternating between the 2 bolts as I tighten, doing them each little by little.
I'm seriously stumped and im wondering if I need to get the mounting area faced. But If that's the case i dont understand how for the first couple of months I had the bike before I started working on it it was in good alignment and worked perfectly fine.
Anyone here have any tips or ideas??