Perhaps thermal overload, but I was having problems with the 7805 until I replaced it when I put in a 5" Nextion. I did not try the heat sink as it required more cutting to fit then I wanted to try. I also planned on additional boards (stand alone signal analyzer and JACKAL, so a higher rated 7805 mounted on the back panel (using the case as the heat sink) worked well for me.?
Mark
