Thermal Runaway and other issues

I've had the gMax 1.5 XT+ for almost a month now, and almost every print is a fresh nightmare. Tech support has been helpful with some of it but really, should it be something every time? Most of it seems to be hardware related.

My hotend #1 gives me a THERMAL RUNAWAY error every time i print something. Randomly in the print. Sometimes after layer 1 sometimes after 9 hours into a 20 hour print. So just for kicks, I used the same gcode on hotend #2 and it printed fine, all 2.5 days of it. Tech support keeps telling me "oh your fan comes on too fast, or unplug and plug it back in" or something like that. Nope. Still gets the THERMAL RUNAWAY error. I don't even know what that means. Anyway, I just went back to hotend #2 bc I need to get something done (wasted a week and tons of material dealing with this THERMAL issue). Well, now #2 has a new issue - it's not pulling the filament though. It prints what's in the nozzle, but then doesn't advance it as it goes along.

Anyone have any solutions for either of these issues? Seriously frustrated with this thing.

Thanks, in advance.
I was having the same thermal runaway issue. For me it was caused by the part cooling fan. The fan shroud was directed towards the heater block, preventing the heater from keeping the hot end at temperature. I printed a new fan shroud and ran PID autotune to fix the issue. To fix your issue, you could start by running PID autotune (M303S200C10), then editing your PID settings in marlin (#define DEFAULT_Kp , #define DEFAULT_Ki , #define DEFAULT_Kd). If that doesn't help, you could try adjusting your thermal runaway settings (#define WATCH_TEMP_PERIOD , #define WATCH_TEMP_INCREASE).