Flipkart - Heating issues with my worth phone Not satisfied Flipkart rejected return

I bought a Samsung S**+ from Flipkart (Seller TrueComRetail). The very first day I recieved it, I felt the body was getting heated like a joke. I did not install a single app, everything was ok default and the metal body wad uncomfortable to hold. Considering the heating issues I requested a return from Flipkart on the very first day I ordered the phone. The customer care called me, I told them about the issue. They had my phone on hold for a long time just to tell me later that due to some technical issues they are not able to apply for return request and asked me to call the next day. I was cool about it and politely agreed. The next day another call, another multiple holds and technical issues but atleast the return request was applied. Then an hour long call with an "executive" who gave me different troubleshooting methods like checking background apps (there were none, obviously), restarting, factory reset. I was cool about all this even tho it took a long hour because these were basic ways to troubleshoot. But nothing helped and they said a "technician" will come, he'll check the phone. If he finds an issue, they will take return. After few * days (today on *th July, the technician came), he again did a few restarts, checked for updates, did a factory reset, the same things that executive told me. Well, if I restart and factory reset a phone multiple times a day, it will obviously work better, but does that make any sense? They he said, he'll run the camera app and if temperature is **°C, return will be approved and someone will come. The temperature was **°C so he rejected, he had an app installed in his phone where he selected "no issues found". I asked if there's chances, he said to contact flipkart. There was an option about "Customer not satisfied with the product" even if no problem is found. He selected it only when I mentioned about it. But he did not submit it in front of me, he just left. He probably reselected "no problems found" and the very next second I got notified that the return is rejected as the technician has "troubleshooted the issue and it's resolved". What? He did not do anything except checking for updates, recording a video and simply taking screenshot of the temperature reading which was just *°C down (and even if it was at **°C, it was really really hot to handle. The metal frame of the phone was boiling). Now, even if according to them it's not overheating. I'm still not satisfied with the product from the very first day of purchase, how can they reject the return? It's not a **k worth of phone that I can simply compromise with and replace after a year. After the rejection, I contacted flipkart via chat this time. First they missed all my long messages due to some "technical issues" (as usual) so I had to resend them. Then again, they asked me to do some troubleshooting steps like the person on the call and the technician did. I'm stuck!