I have the same issue. Mine was working for a few months, got stuck while watching a movie, I hit the home key but nothing happened then unplugged it, plugged it back in, stayed on the boot screen for 2 hrs.
@mikeydino63, if you're using the TV's USB port to power the Roku try using the supplied power adapter (or vice versa, although the supplied power adapter should be best). If that doesn't help, a factory reset may be in order.
I have the same problem with my Express 4K+ plugged into a wall outlet. It has been working fine since I bought it new a couple of months ago but tonight the TV screen froze as we were watching a Netflix movie. The blue light on the Express flashed a few times and then went out and I have not been able to get it to come back on since then. I have tried unplugging and re-plugging the power cable and pressing the factory reset button for more than 10 s, all to no avail. The TV says that there is no signal coming from the Express unit and the screen stays black.
The unit is Model 3941X and the serial number is SO7P2195DK6F.