As with many Chinese-made products, these are sold under several brand names.
There is a YouTube video, apparently from a seller, claiming that the E3 error code that my unit displays a few seconds after turn-on can be corrected by removing the bezel containing the switches and display and reattaching one of the two connectors that may have come loose. This was not the case in my unit. Everything seems to work as far as charging and display readout, but once E3 shows up on the screen, the boot-up stops and the massager motor will not operate. Nothing works further except the button to turn the unit off.
Anyone have a solution for this?