Display screen locked and cannot reset. Should I upgrade/flash firmware?

Hello,

I have a tevo black widow and the entire hot end got clogged up in a ball of nylon filament.



When this happened, the printer showed a MAXTEMP error message and the screen is locked, meaning I cannot change screens.

so I REPLACED THE ENTIRE HOTEND.



It still shows the MAXTEMP error message and is still unresponsive.



I of course tried pressing the reset button but it flashes and restarts but goes right to the same error message.




I thought when I replaced the entire hot that would solve the problem as I thought a wire had gotten damaged from the failed print filament.



Any help would be appreciated!!

THanks!
https://content.invisioncic.com/ulti...1e63f40cb8.jpg