Printer keeps shutting off and target temp drops to 140°

Ok i have tried everything and now just frustrated. I have reset the firmware and the printer. Changed the fan and it keeps stopping with this one print. It’s a box about 190 mm. I have tried in different slicers not the problem. Remade it in fusion twice just in case. I can print smaller stuff and no problem. Maybe because it’s a long print? Something keeps triggering it to stop. Please any help would be appreciated before I toss it off the balcony!