15 pro max suddenly using excess resources/power while on and even when OFF. Dies overnight. Days out of warranty 👌🏽

Went on 3 wk trip to France/UK. One day, two weeks into trip I noticed my perfect condition pro max 15 was suddenly getting hot in my pocket. Took it out and noticed battery was draining faster than the previous year of ownership and the previous 2 weeks of the trip using the same apps (airalo for data, IDF/RATP apps for metro, and google maps). Googled for solutions and tried literally everything. Turned off background app usage. No change. Put in airplane mode. No change. You name it and I tried it. Battery app says "normal" 94% health so I don't think it's a "battery problem", but other hardware or software. I reset it to factory condition. No change. I restored it with iCloud. No change. I did a UDF restore. No change. Then I realized that if I turned it off (press power button and volume + button and then moved power off slider) with 100% battery and not connected to the charger, it stayed slightly warm all night and drained the battery overnight to the point of about 5% in the morning. I did the chat with apple support and they ran the diagnostics on the phone and said they saw no problems so they set up an appt for me at a local Paris Apple Store. The employee at the store used and iPad and checked the phone and said they saw no issues. I sort of expected them to physically connect it to some device in order to see if something was causing the cpu or other chip/etc to continually use excess power/resources when powered off (since phones are rarely "really" off), but no such luck. My 1 yr warranty ran out within a few days before this happened and after having several iPhones over many years with zero issues, I didn't get AppleCare. Trying to figure out my next step. I still owe $700 on this thing! Sounds like hardware on the motherboard is bad. Nice