My 2017 TCL 55P607 has worked great until now, when all I get is a blank gray screen. Attempts to reset it by plugging and unplugging and pressing the reset button haven't changed anything. Because the screen is blank, I don't have access to any of the menus. The only recent configuration change is that earlier today I added two Roku wireless speakers, which connected easily. However, I believe installing the speakers triggered some kind of system update. Could this be the problem? If so, can you roll it back?