The issue can be related to mechanical movements, sensors, scan axis, web server. PleaseStart the printer without printheads, supplies and external connections. Parts to be replaced are multiple at this point, please check what the printer is doing just before it freezes to get more information about what could be failing.
Also check the status of Power supply LED, FORMATTER LED1, LED2, LED3 and status of control panel because based on that only the faulty part can be suspected
It is the same exact engine between those 2 models. I typically reboot the printer and when the carriage leaves home position during the bootup process I turn it off by the main switch in back, then you can access the printheads. Make sure you also remove the paper as that can hang the system up also.